Cope if platform declares mbstowcs_l(), but not locale_t, in <xlocale.h>.

Previously, we included <xlocale.h> only if necessary to get the definition
of type locale_t.  According to notes in PGAC_TYPE_LOCALE_T, this is
important because on some versions of glibc that file supplies an
incompatible declaration of locale_t.  (This info may be obsolete, because
on my RHEL6 box that seems to be the *only* definition of locale_t; but
there may still be glibc's in the wild for which it's a live concern.)

It turns out though that on FreeBSD and maybe other BSDen, you can get
locale_t from stdlib.h or locale.h but mbstowcs_l() and friends only from
<xlocale.h>.  This was leaving us compiling calls to mbstowcs_l() and
friends with no visible prototype, which causes a warning and could
possibly cause actual trouble, since it's not declared to return int.

Hence, adjust the configure checks so that we'll include <xlocale.h>
either if it's necessary to get type locale_t or if it's necessary to
get a declaration of mbstowcs_l().

Report and patch by Aleksander Alekseev, somewhat whacked around by me.
Back-patch to all supported branches, since we have been using
mbstowcs_l() since 9.1.

1 files changed, 53 insertions, 0 deletions

diff --git a/configure b/configure
index 048599f1e4..04f987d393 100755
--- a/configure
+++ b/configure
@@ -11557,6 +11557,59 @@ $as_echo "#define GETTIMEOFDAY_1ARG 1" >>confdefs.h
 
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for wcstombs_l declaration" >&5
+$as_echo_n "checking for wcstombs_l declaration... " >&6; }
+if ${pgac_cv_func_wcstombs_l+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdlib.h>
+#include <locale.h>
+int
+main ()
+{
+#ifndef wcstombs_l
+(void) wcstombs_l;
+#endif
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_func_wcstombs_l='yes'
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdlib.h>
+#include <locale.h>
+#include <xlocale.h>
+int
+main ()
+{
+#ifndef wcstombs_l
+(void) wcstombs_l;
+#endif
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_func_wcstombs_l='yes (in xlocale.h)'
+else
+  pgac_cv_func_wcstombs_l='no'
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_func_wcstombs_l" >&5
+$as_echo "$pgac_cv_func_wcstombs_l" >&6; }
+if test "$pgac_cv_func_wcstombs_l" = 'yes (in xlocale.h)'; then
+
+$as_echo "#define WCSTOMBS_L_IN_XLOCALE 1" >>confdefs.h
+
+fi
 
 # Some versions of libedit contain strlcpy(), setproctitle(), and other
 # symbols that that library has no business exposing to the world.  Pending