Some of these were doing nothing useful at all. I removed those.
A couple were protecting static data, and I fixed those to use Mutex
and MutexGuard properly.

Change-Id: I444d13f8b6c50e526cce8d69d09aeaf240e5c6ca
Reviewed-on: https://gerrit.libreoffice.org/3678Reviewed-by: Tor Lillqvist <tml@iki.fi>
Tested-by: Tor Lillqvist <tml@iki.fi>