Fix for CONC-99: memory corruption

  In case a connection fails and vio was already created the socket needs to be closed
  only via vio_close. A 2nd close may lead to corruption in a threaded evironment in case
  the handle was opened by a nother thread.

Author: holzboote@googlemail.com

libmariadb/libmariadb.c

@@ -1704,7 +1704,6 @@ MYSQL *mthd_my_real_connect(MYSQL *mysql, const char *host, const char *user,
     {
       my_set_error(mysql, CR_CONN_HOST_ERROR, SQLSTATE_UNKNOWN, ER(CR_CONN_HOST_ERROR),
                           host, socket_errno);
-      closesocket(sock);
       goto error;
     }
   }