Related bnc#822625: Cache FontEntry with the original FontSelectPattern.

Otherwise we do not hit cache directly, only after expensive call to
ImplFindByFont.

(cherry picked from commits a6b00d16eb27a5e7e31c721671001a909ecef960
and 16a62079018aea0e72636bdb00576487b4e830b9)

Change-Id: If15b368feeba94c8fff8ee7cbe049fc4a2069768
Reviewed-on: https://gerrit.libreoffice.org/9520
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>