Submitting a patch made by Aleric Inglewood (See VWR-14914).

This bug happens for a lot of people, although it might be needed to have a fast multi core machine.
I have seen it on 1.22.10 once, never used 1.23 sorry, and saw it often on snowglobe. I am sure
it also affects 1.23 but I'd have to test that.

The symptons are that on a viewer with normally a good, high FPS, sometimes it happens
that the FPS dramatically drops (as low as 0.3, but it can also be anything higher, as high
as 10, say).

This particular jira is about a problem where the main thread is slowed down by a mutex lock
in libopenal (most calls starting with 'al' in indra/llaudio/audioengine_openal.cpp and
one in indra/llaudio/listener_openal.cpp). You can see that this is the case by opening the
Frame Console (control-shift-2) and checking that the "audio" (and possibly misc) timings
are very large compared to the Render time.