The PRODUCT_BUNDLE_IDENTIFIER property was not defined in the Xcode
project file and therefore the build would fail.

This fixes a regression introduced by 0749ba2c

.

Task-number: QTBUG-65673
Change-Id: I8089b36d86588223ec34859af7388c99a3574d8b
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>