Remove Deinterlace routines from old place (modules/codec/ffmpeg/video_filter.c), because they have moved to their own file (modules/codec/ffmpeg/deinterlace.c).

Make /sbin/ldconfig explicite as scriptlet and don't use the advanced syntax, which isn't supported on RHEL.

Enhance contrib system with package-rpm build target and system. RPM packages are build in extras/contrib/src/rpm/RPMS and extras/contrib/src/SRPMS.