Revert "Use relative path for QMAKE_BUNDLE_DATA"

turns out that a relative path makes some versions of Xcode crash.
so use an absolute path again.
fileFixify() has been fixed for shadow builds to make this possible.

This reverts commit 6ccf0a32

.

Task-number: QTBUG-45424
Change-Id: Ica87c6c29f990f56e42c399b6d9b1c7eacdd13a7
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>