Bug #36887: Typo in mysql_client_test.c uses bind instead of my_bind

There was a typo in a error check causing wrong thing to be ckecked 
and a possible error not being caught.
Fixed by using the correct variable to test for malloc() errors. 

tests/mysql_client_test.c

@@ -11675,7 +11675,7 @@ static void test_bug5194()
                         MAX_PARAM_COUNT * CHARS_PER_PARAM + 1);
   param_str= (char*) malloc(COLUMN_COUNT * CHARS_PER_PARAM);
 
-  if (bind == 0 || query == 0 || param_str == 0)
+  if (my_bind == 0 || query == 0 || param_str == 0)
   {
     fprintf(stderr, "Can't allocate enough memory for query structs\n");
     if (my_bind)