attempt to further reduce unnecessary allocation and
freeing of OUString.

Change-Id: I85169cfcd2311a5e6a96dc0292ce0686d1b0e43d
Reviewed-on: https://gerrit.libreoffice.org/34092Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Jenkins <ci@libreoffice.org>