Update ffmpeg and lang.

Updates ffmpeg to https://github.com/hrydgard/ppsspp-ffmpeg/commit/6cffc1f6012e0091f46c031a023e877d621f83e4.

Updates lang to https://github.com/hrydgard/ppsspp-lang/commit/447571dd9a44f6370670ef1b12c1426bd8732ba0.

Nothing special, just routine updates.