Related bnc#822625: Cache minimum height for table cells.

Change-Id: I35e295347a046376289f5d4fd5468860d0b8f0ae
(cherry picked from commit 5792e76cb5beb630c135f57b74f57d74dd2dc2b0)
Reviewed-on: https://gerrit.libreoffice.org/9519
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>