This reverts commit 5b2cb23c.

That did not fix the bug (fdo#47021), but apparently it does cause
problems, such as the failure of the sfx2 DocumentEvents test (that
doesn't crash any more since 228a3f8b);
without the SolarMutexReleaser the test doesn't fail for me.
(cherry picked from commit a1d493fa)
Signed-off-by: Stephan Bergmann <sbergman@redhat.com>