This prevents errors from ms sdk sal_supp.h: warning '__useHeader': macro redefinition

Change-Id: I122bbf6171c73d77970a549353dca67dd26d0300
Reviewed-on: https://gerrit.libreoffice.org/24055Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Oliver Specht <oliver.specht@cib.de>