ac_check_define.m4: remove stray AC_DEFINE outside of the macro definition

cf.: bug #5234 -- generated configure script does not change.

acinclude/ac_check_define.m4

@@ -11,4 +11,4 @@ YES_IS_DEFINED
     AC_DEFINE([HAVE_$1],[],[Added by AC_CHECK_DEFINE])
   fi
 ])dnl
-AC_DEFINE([HAVE_$1],[],[Added by AC_CHECK_DEFINE])
+