Memory leak in mysql_close() with MYSQL_OPT_NONBLOCK

When a mysql connection is created and is set to not blocking, mysql_close() doesn't free the memory associate with async causing a severe memory leak.

Depending from the the speed of your CPU and your available memory, the follow code can eat all available memory in just few seconds:

#include <mysql.h>

#include <stdio.h>

int main() {

  while(1) {

  MYSQL *mysql=mysql_init(NULL);

  mysql_options(mysql, MYSQL_OPT_NONBLOCK, 0);  // this line triggers the bug

  mysql_close(mysql);

  }

  return 0;

}