Simple cleanups

Fixed compiler warning
Added comment

extra/mysqld_safe_helper.c

@@ -14,7 +14,7 @@ void my_exit(int c)
   exit(c);
 }
 
-void do_usage()
+void do_usage(void)
 {
   printf("Usage:\n"
          "  %s <user> log  <filename>\n"
@@ -59,7 +59,7 @@ int main(int argc, char *argv[])
   MY_INIT(argv[0]);
 
   if (argc < 3)
-    do_usage(argv[0]);
+    do_usage();
 
   user_info= my_check_user(argv[1], MYF(0));
   if (user_info ? my_set_user(argv[1], user_info, MYF(MY_WME))

sql/sql_parse.cc

@@ -3012,7 +3012,7 @@ static int mysql_create_routine(THD *thd, LEX *lex)
     return false;
   }
 #ifdef WITH_WSREP
-error:
+error: /* Used by WSREP_TO_ISOLATION_BEGIN */
 #endif
   return true;
 }