vcl-quartz: fix build of recently introduced DrawTextSpecial for OSX<10.6

Change-Id: I277d9e2f385b712001385e115b22f6fbb8106ae5
Reviewed-on: https://gerrit.libreoffice.org/8790
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>