[BUG] pulseaudio mutex lock issue is back

[Bob Tracy <rct@gherkin.frus.com>]

Our old friend is back:

Assertion 'pthread_mutex_unlock(&m->mutex) == 0' failed at pulsecore/mutex-posix.c:106, function pa_mutex_unlock(). Aborting.

An easy way to reproduce: run either firefox or iceweasel, then click on
the drop-down menu in the upper-left corner -- the application
immediately aborts with the above message.  If the historical pattern
holds, this should affect any application that nominally has sound
capabilities, and usually appears after upgrades to gcc and/or glibc
have been applied.  More rarely, kernel version changes have been
successfully blamed.

--Bob