Fix error loading res_monitor.

For some odd reason, loading app_mixmonitor was fine, but res_monitor was not.
This patch fixes a set of issues related to func_periodic_hook exporting the
beep functions that gets res_monitor working again.



git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@412910 f38db490-d61c-443f-a65b-d21fe96a405b