Apply a patch that fixes a test for MariaDB 10.0.11

Redmine: fixes #2552
Redmine: ref #2385

MariaDB 10.0.11 shows an int system variable mroonga_lock_timeout as
a signed integer. Note that MySQL and MariaDB 10.0.x (x < 11) show it
as an unsigned integer, for example,
  SHOW GLOBAL VARIABLES LIKE "mroonga_lock_timeout";
shows 4294967295 if mroonga_lock_timeout = -1.

The patch is written by Toshihisa Tashiro. Thanks!!!