• Update the MASTER_SITES to fix the fetch.
• Fix the build if multimedia/x264 is installed in system. [1]
• Add --exclude in extract to not extract beos, macosx, liba52, libavcodec, libdvdcss and other un-need directories to make sure they do build with the system (use external dependencies) libraries. Only keep libx264.
• Remove a few missing leftover of ffmpeg in post-patch and in one of patch.
• Add '-dx' in jam by default to give the verbose of build. Easier for me to collect the bug report or/and read in log from tinderboxes.
• Clean distinfo, remove a leftover of ffmpeg and add SHA256.
• Clean pkg-descr to make it looks nicer.
• Make portlint a bit happier.

Before anyone ask/request me to update it to 7.x. I don't know yet, I haven't
dig in what 7.x has. I think, this port needs to have a good last clean up
before update it to 7.x.

PR: ports/88838 [1]
Reported by: Zach Dykstra <md@anduin.org> [1], bite on me too