Bug#26243 mysql command line crash after control-c

- Backported the 5.1 DBUG to 5.0.
- Avoid memory cleanup race on Windows client for CTRL-C

tests/mysql_client_test.c

@@ -16673,7 +16673,6 @@ int main(int argc, char **argv)
 {
   struct my_tests_st *fptr;
 
-  DEBUGGER_OFF;
   MY_INIT(argv[0]);
 
   load_defaults("my", client_test_load_default_groups, &argc, &argv);