server font dtor always calls ReleaseFaceFT

therefore we must always call GetFaceFT in the ctor
and not return early *before* calling GetFaceFT which
could happen in case of inane font size requests, i.e.

if( (mnWidth < 0) || (mfStretch > +64.0) || (mfStretch < -64.0) )

valgrind+bff

Change-Id: If22f8f7ff6aaed3ffa9eec68630da8601dfd5cae
(cherry picked from commit 884229ed3ee2f84eb052c866e22bdb242a385788)
Reviewed-on: https://gerrit.libreoffice.org/11400
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>