multimedia/mlt7: Disable clang-scan-deps
This fixes build on 14.3, since clang-scan-deps is not in base. We don't
really need it here, so remove the complicated logic.
multimedia/mlt7-glaxnimate: Fix qt5 flavor
It was trying to build MOD_QT6 which wasn't explicitly disabled.
Remove unneeded deps from qt6 flavor.
Fixes: 4488884ee060 - multimedia/mlt7: Update to 7.34.1