PT44376021 - Race in resources deallocation from OsTimer

Fixed the resources deallocation order in OsTimer. The mutex that guards timer service
was made static so it can outlive all timers and the timer service. The timer service
will not stop when requested if at that moment there are active timers (if it will be
stopped it will corrupt remaining timers memory). We rather leak memory than corrupt
something.

Main body in sipXpark was enclosed in {} to make sure all timers are deleted before
terminating the service.
Merge commit 'tags/separation_of_timer_race_fixx' into release-4.6