Generalize the dcc_{r,x}_argv routines so they can be used to
transfer arbitrary array-of-strings tokens (useful for protocol
hacking experiments; no functional change).

This will hopefully fix issue 39 <http://code.google.com/p/distcc/issues/detail?id=39>.
Some header files were using #if statements that depended on macros defined in config.h
without #including config.h first.  The result was a compilation error, because
"#if !HAVE_DECL_SNPRINTF" was evaluating to true because config.h hadn't been included,
causing us to declare snprintf() when we shouldn't, leading to a conflict with the
declaration in the standard header files.

(The alternative solution would have been to add "#include <config.h>"
to every header file that uses '#if'.  I decided not to do that, just
for consistency with the existing code.)

add a new "--scan-includes" option to distcc which shows
which headers distcc would send to the remote machine in
pump mode, without actually compiling anything.

(typically the only change is in the FSF street address).  Add Google
copyright line in some places it was missing.  Add GPLv2 notice to
avahi patches.

OKed by fergus

common setup errors.

In pump script:
  - If DISTCC_HOSTS is set, print out a message saying how many hosts
    there are (similar to the one that we already print if you instead
    set DISTCC_POTENTIAL_HOSTS) and how many of them have pump enabled.
  - Report an error if you run pump using a host list containing no
    hosts with ',cpp'.  (Should this be a warning instead?)
  - Report an error if you run pump using an empty host list.
    (Should this be a warning instead?)

In distcc client:
  - Improve the warning messages that you get if you run distcc using
    hosts with ",cpp" without running pump.

Also, fix the emacs var-setting line: it was missing a semicolon
before, which means the entire line was being ignored.

No contentful change.

Reviewed by fergus@google.com

lines.  Fixed up resulting mis-indented code I noticed (mostly in
files that used 8 space indents, or used 4-space and 8-space indents
in the same file (!)).  Added the emacs tab-var setting for all files,
not just some of them.

I also added in copyright notices for files I noticed that didn't have
them.  We'll want to do another pass-through to fix these up properly,
though.

I used the following perl snippet to check for mis-indented code after
converting tabs to whitespace:

  $ for i in *.{c,h}; do echo $i; perl -nle 'if ($indent > 0) {$sp=" " x $indent; /^$sp[^ ]/ && print "$.: $_"; $indent=0;}; if (/^( *).*{/ ) {$indent=length($1);} else {$indent=0;}' $i; done | less

It had false positives, but hopefully didn't miss anything.

Reviewed by klarlund@google.com

level.  I'm doing this in two stages, because I don't understand svn
enough to be confident to do it in one.  This first stage just copies
all the files from distcc/FOO to FOO.  Now there are two copies of
each file under distcc; the Makefile/etc uses the one in distcc and
ignores the one at the top level.

The next commit will delete everything under distcc, and rewrite the
Makefile/etc to use the top-level versions instead.