removed maintainer-mode quirks

-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-maintainer-mode and enable maintainer-specific
-dnl settings.
-
-AC_DEFUN(MU_MAINTAINER_MODE,
-  [AM_MAINTAINER_MODE
-   if test x"$USE_MAINTAINER_MODE" = xyes; then
-     if test x"$GCC" = xyes; then
-       AC_MSG_CHECKING(whether gcc accepts -ggdb)
-       CFLAGS="-ggdb"
-       AC_TRY_COMPILE([],void f(){},
-                      AC_MSG_RESULT(yes),
-		      [if test x"$ac_cv_prog_cc_g" = xyes; then
-                         CFLAGS=-g
-                       else
-                         CFLAGS=
-                       fi
-		       AC_MSG_RESULT(no)])
-       CFLAGS="$CFLAGS -DMAINTAINER_MODE"
-     fi
-   fi])