addons/res_config_mysql: silense warnings about printf format errors.

addons/res_config_mysql: silense warnings about printf format errors.

Warnings without this:

res_config_mysql.c: In function 'update2_mysql':
res_config_mysql.c:741:15: warning: format '%llu' expects argument of type
    'long long unsigned int', but argument 6 has type 'my_ulonglong'
    {aka 'long unsigned int'} [-Wformat=]
ast_debug(1, "MySQL RealTime: Updated %llu rows on table: %s\n",
    numrows, tablename);

(reformatted for readability within line-wrap)

Change-Id: I2af4d419a37c1a7eeee750cf9ae4a9a2b3a37fd3