Revert "CppunitTest_sw_ooxmlexport: disable failing check on Mac for now"

Re-enable the unit test with the fixed xPath expression.

This reverts commit 0e5f9958a57a68a3707db5b1eb9f82e0326327c1.

Conflicts:

	sw/qa/extras/ooxmlexport/ooxmlexport.cxx

Change-Id: Ibc848b2ae89b3fb7f009cd984d0ecc5fc165673a
Reviewed-on: https://gerrit.libreoffice.org/8679
Tested-by: LibreOffice gerrit bot <gerrit@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>