Handle --enable-debug option. When the option is specified,

adds -ggdb to the invocation of	gcc, and removes any optimization
directives from CFLAGS.

+dnl This file is part of GNU mailutils.
+dnl Copyright (C) 2001 Free Software Foundation, Inc.
+dnl
+dnl This file is free software; as a special exception the author gives
+dnl unlimited permission to copy and/or distribute it, with or without
+dnl modifications, as long as this notice is preserved.
+dnl
+dnl This program is distributed in the hope that it will be useful, but
+dnl WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+dnl implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+dnl
+dnl Check for --enable-debug switch. When the switch is specified, add
+dnl -ggdb to CFLAGS and remove any optimization options from there.
+dnl 
+
+AC_DEFUN(MU_DEBUG_MODE,
+  [AC_ARG_ENABLE(debug,                     
+    [  --enable-debug          enable debugging mode],
+    [if test x"$enableval" = xyes; then
+       if test x"$GCC" = xyes; then
+	 AC_MSG_CHECKING(whether gcc accepts -ggdb)
+         save_CFLAGS=$CFLAGS
+         CFLAGS="-ggdb"
+         AC_TRY_COMPILE([],void f(){},
+           AC_MSG_RESULT(yes),
+           [if test x"$ac_cv_prog_cc_g" = xyes; then
+              CFLAGS=-g
+            else
+              CFLAGS=
+            fi
+            AC_MSG_RESULT(no)])
+         CFLAGS="`echo $save_CFLAGS | sed 's/-O[[0-9]]//g'` $CFLAGS"
+       fi
+     fi])])