[man pages]: Define page-local `MR` fallback.

[man pages]: Provide page-local fallback definition of new `MR` macro.
I didn't think I was going to have to do this, but the premier site on
the web for viewing Linux man pages, Michael Kerrisk's man7.org, has
been pulling snapshots of the pages themselves without upgrading the
underlying macros, and so man page cross references set with `MR` are
getting lost in its presentations.  (I acknowledge: Ingo Schwarze warned
me something like this could happen.)  This definition is intended as a
stopgap measure only.  I want to revert this after groff 1.23 is
released and has spread to some reasonable degree.

* contrib/chem/chem.1.man:
* contrib/eqn2graph/eqn2graph.1.man:
* contrib/gdiffmk/gdiffmk.1.man:
* contrib/glilypond/glilypond.1.man:
* contrib/gperl/gperl.1.man:
* contrib/gpinyin/gpinyin.1.man:
* contrib/grap2graph/grap2graph.1.man:
* contrib/hdtbl/groff_hdtbl.7.man:
* contrib/mm/groff_mm.7.man:
* contrib/mm/groff_mmse.7.man:
* contrib/mm/mmroff.1.man:
* contrib/mom/groff_mom.7.man:
* contrib/pdfmark/pdfroff.1.man:
* contrib/pic2graph/pic2graph.1.man:
* contrib/rfc1345/groff_rfc1345.7.man:
* man/groff.7.man:
* man/groff_char.7.man:
* man/groff_diff.7.man:
* man/groff_font.5.man:
* man/groff_out.5.man:
* man/groff_tmac.5.man:
* man/roff.7.man:
* src/devices/grodvi/grodvi.1.man:
* src/devices/grohtml/grohtml.1.man:
* src/devices/grolbp/grolbp.1.man:
* src/devices/grolj4/grolj4.1.man:
* src/devices/gropdf/gropdf.1.man:
* src/devices/gropdf/pdfmom.1.man:
* src/devices/grops/grops.1.man:
* src/devices/grotty/grotty.1.man:
* src/devices/xditview/gxditview.1.man:
* src/preproc/eqn/eqn.1.man:
* src/preproc/eqn/neqn.1.man:
* src/preproc/grn/grn.1.man:
* src/preproc/pic/pic.1.man:
* src/preproc/preconv/preconv.1.man:
* src/preproc/refer/refer.1.man:
* src/preproc/soelim/soelim.1.man:
* src/preproc/tbl/tbl.1.man:
* src/roff/groff/groff.1.man:
* src/roff/nroff/nroff.1.man:
* src/roff/troff/troff.1.man:
* src/utils/addftinfo/addftinfo.1.man:
* src/utils/afmtodit/afmtodit.1.man:
* src/utils/grog/grog.1.man:
* src/utils/hpftodit/hpftodit.1.man:
* src/utils/indxbib/indxbib.1.man:
* src/utils/lkbib/lkbib.1.man:
* src/utils/lookbib/lookbib.1.man:
* src/utils/pfbtops/pfbtops.1.man:
* src/utils/tfmtodit/tfmtodit.1.man:
* src/utils/xtotroff/xtotroff.1.man:
* tmac/groff_man.7.man.in:
* tmac/groff_me.7.man:
* tmac/groff_ms.7.man:
* tmac/groff_trace.7.man:
* tmac/groff_www.7.man: Do it.

The sed script I used follows.  I patched neqn(1), which does not
require compatibility mode, by hand.

/^\.cp 0/a\
.\
.\\" Define fallback for groff 1.23's MR macro if the system lacks it.\
.de @@\
.  de MR\
.    ie \\n(.$=1 \\\
.      I \%\\$1\
.    el \\\
.      IR \%\\$1 (\\$2)\\$3\
.  \\\\.\
..\
.if  \\n(.g .if !d MR .@@\
.if !\\n(.g .@@\
.rm @@

10 files changed, 130 insertions, 0 deletions

diff --git a/src/utils/addftinfo/addftinfo.1.man b/src/utils/addftinfo/addftinfo.1.man
index 3cad99a3c..9b3c24460 100644
--- a/src/utils/addftinfo/addftinfo.1.man
+++ b/src/utils/addftinfo/addftinfo.1.man
@@ -32,6 +32,19 @@ fonts for use with
 .do nr *groff_addftinfo_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/afmtodit/afmtodit.1.man b/src/utils/afmtodit/afmtodit.1.man
index 79b18feab..45402f851 100644
--- a/src/utils/afmtodit/afmtodit.1.man
+++ b/src/utils/afmtodit/afmtodit.1.man
@@ -31,6 +31,19 @@ PostScript and PDF output
 .do nr *groff_afmtodit_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/grog/grog.1.man b/src/utils/grog/grog.1.man
index abd020604..7f5f4bcab 100644
--- a/src/utils/grog/grog.1.man
+++ b/src/utils/grog/grog.1.man
@@ -28,6 +28,19 @@ command a document requires
 .do nr *groff_grog_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/hpftodit/hpftodit.1.man b/src/utils/hpftodit/hpftodit.1.man
index e645beb7b..058d86c60 100644
--- a/src/utils/hpftodit/hpftodit.1.man
+++ b/src/utils/hpftodit/hpftodit.1.man
@@ -32,6 +32,19 @@ and
 .do nr *groff_hpftodit_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/indxbib/indxbib.1.man b/src/utils/indxbib/indxbib.1.man
index dd14ac164..dffdee900 100644
--- a/src/utils/indxbib/indxbib.1.man
+++ b/src/utils/indxbib/indxbib.1.man
@@ -29,6 +29,19 @@
 .do nr *groff_indxbib_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/lkbib/lkbib.1.man b/src/utils/lkbib/lkbib.1.man
index 6d485729d..1c16d7de9 100644
--- a/src/utils/lkbib/lkbib.1.man
+++ b/src/utils/lkbib/lkbib.1.man
@@ -29,6 +29,19 @@ lkbib \- search bibliographic databases
 .do nr *groff_lkbib_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/lookbib/lookbib.1.man b/src/utils/lookbib/lookbib.1.man
index fcbb739d2..d0e24d745 100644
--- a/src/utils/lookbib/lookbib.1.man
+++ b/src/utils/lookbib/lookbib.1.man
@@ -29,6 +29,19 @@
 .do nr *groff_lookbib_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/pfbtops/pfbtops.1.man b/src/utils/pfbtops/pfbtops.1.man
index 61314a8b9..c1340fe59 100644
--- a/src/utils/pfbtops/pfbtops.1.man
+++ b/src/utils/pfbtops/pfbtops.1.man
@@ -30,6 +30,19 @@ Font ASCII
 .do nr *groff_pfbtops_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis
diff --git a/src/utils/tfmtodit/tfmtodit.1.man b/src/utils/tfmtodit/tfmtodit.1.man
index 3bc5ad092..eba2044b8 100644
--- a/src/utils/tfmtodit/tfmtodit.1.man
+++ b/src/utils/tfmtodit/tfmtodit.1.man
@@ -32,6 +32,19 @@ and
 .do nr *groff_tfmtodit_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .\" Definitions
diff --git a/src/utils/xtotroff/xtotroff.1.man b/src/utils/xtotroff/xtotroff.1.man
index f598f4896..b842eaf43 100644
--- a/src/utils/xtotroff/xtotroff.1.man
+++ b/src/utils/xtotroff/xtotroff.1.man
@@ -31,6 +31,19 @@ font metrics
 .do nr *groff_xtotroff_1_man_C \n[.cp]
 .cp 0
 .
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.de @@
+.  de MR
+.    ie \n(.$=1 \
+.      I %\$1
+.    el \
+.      IR %\$1 (\$2)\$3
+.  \\.
+..
+.if  \n(.g .if !d MR .@@
+.if !\n(.g .@@
+.rm @@
+.
 .
 .\" ====================================================================
 .SH Synopsis