proposed comments for stdarg module

[Paul Eggert]

Here's a proposed patch to the stdarg module description, to describe
the benefits of using AC_PROG_CC_STDC with this module.

2007-02-04  Paul Eggert  <address@hidden>

        * modules/stdarg (configure.ac): Add comment suggestiong
        AC_PROG_CC_STDC.

--- modules/stdarg.~1.1.~       2006-05-08 06:13:13.000000000 -0700
+++ modules/stdarg      2007-02-04 09:39:15.000000000 -0800
@@ -7,6 +7,12 @@ m4/stdarg.m4
 Depends-on:
 
 configure.ac:
+dnl AC_PROG_CC_STDC should be added quite early to configure.ac.
+dnl Some compilers (e.g., AIX 5.3 cc) need to be in c99 mode
+dnl for the builtin va_copy to work.  With Autoconf 2.60 or later,
+dnl AC_PROG_CC_STDC arranges for this.  With older Autoconf AC_PROG_CC_STDC
+dnl shouldn't hurt, though installers are on their own to set c99 mode.
+dnl
 gl_STDARG_H
 
 Makefile.am: