The source includes shouldn't be used by installations, so
don't install the extra file, but only use it if the package
is used from the build-dir.
Task-number: QTBUG-33970
Change-Id: I08f91b8a716e935cb04d1233d44cf5c092e240ce
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
