The "hides" the hack for native Windows dialogs introduced in
commit 5bb798a9 ("tdf#117295 WIN no main loop shortcut for
OLE dialog") in its own header.

Change-Id: I1f36aad20dec50ae1f296001b51085989afb19f6
Reviewed-on: https://gerrit.libreoffice.org/65100
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>