Deprecated in favour of comphelper::SolarMutex

Change-Id: I159077562660de5df25601fa471447f4b64a2cf1
Reviewed-on: https://gerrit.libreoffice.org/24079Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>