xfree: move xfree() function to xmalloc.c

Signed-off-by: whzhe <wanghongzhe@huawei.com>

src/gpasswd.c

@@ -123,12 +123,6 @@ static void log_gpasswd_success (const char *suffix);
 static void log_gpasswd_success_system (/*@null@*/unused void *arg);
 static void log_gpasswd_success_group (/*@null@*/unused void *arg);
 
-static void xfree(void* p) {
-	if (p) {
-		free(p);
-	}
-}
-
 /*
  * usage - display usage message
  */