gmacros.h patch

[Eric Lemings <eric b lemings lmco com>]

A software package that uses GLib and GNU C++ with the AC_C_CONST
macro will cause compile errors because AC_C_CONST says that the
const keyword is broken and undefines it.
--- gmacros.h.orig      Thu Apr 12 13:50:57 2001
+++ gmacros.h   Thu Apr 12 13:52:08 2001
@@ -59,8 +59,10 @@
   __attribute__((format_arg (arg_idx)))
 #define G_GNUC_NORETURN                         \
   __attribute__((noreturn))
+#ifdef const
 #define G_GNUC_CONST                            \
   __attribute__((const))
+#endif
 #define G_GNUC_UNUSED                           \
   __attribute__((unused))
 #else   /* !__GNUC__ */