Added more Xcode specific files to .gitignore.
Made some properties common in gbuil-to-ide to avoid code duplication/bugs.
Xcode projects are broken for now.

Change-Id: I9530435ffe54158ae68ddae0581ac68f968af235
Reviewed-on: https://gerrit.libreoffice.org/15694Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>