Fix savestring & gdb conflict

Moreover, this fix not breaks any pgm which uses readline's savestring

gnu/lib/libreadline/readline.c

@@ -3362,13 +3362,10 @@ rl_getc (stream)
 }
 
 #if !defined (SHELL)
-#ifdef savestring
-#undef savestring
-#endif
 /* Backwards compatibilty, now that savestring has been removed from
    all `public' readline header files. */
 char *
-savestring (s)
+rl_savestring (s)
      char *s;
 {
   return ((char *)strcpy (xmalloc (1 + (int)strlen (s)), (s)));

gnu/lib/libreadline/readline.h

@@ -283,7 +283,8 @@ extern int rl_forced_update_display ();
 #define RL_PROMPT_END_IGNORE	'\002'
 
 #if !defined (savestring)
-extern char *savestring ();	/* XXX backwards compatibility */
+#define savestring rl_savestring        /* XXX backwards compatibility */
 #endif
+extern char *rl_savestring ();
 
 #endif /* _READLINE_H_ */