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