Fix mksrc.sh

Packaging the super repo (qt5.git) itself was broken when creating
split packages. Make the script produce the "split package" also from
the super repo itself.

Change-Id: I5f59398a2f41f0c85349dc669a9eafc03f98e52c
Reviewed-by: Samuli Piippo <samuli.piippo@digia.com>
Reviewed-by: Kalle Viironen <kalle.viironen@digia.com>
Reviewed-by: Antti Kokko <antti.kokko@digia.com>