Cosmetics: Remove two useless casts.
ffmpeg/libavresample: fixed 5.1 to stereo downmixing (there was no center channel).
Revert 657aacfa36, d8ca51c874, fdb28963f6, 2f08327770 commits.
Apply the patch by Aleksoid.
Revert "ffmpeg/libavresample: fixed 5.1 to stereo downmixing (there was no center channel)."

This reverts commit afaf886c1430b14d1cbe5cd4bba4261bab3c2941.

There was no proper review before pushing it.
Revert "actually disable C4995 and C4996 for udf.cpp"

This reverts commit 03ca3eff5fccbfe6bfc1583789d4fe91af8b1900.
build.bat, mpc-hc_setup.iss : add ICL13 support
use the _countof macro when it makes sense to do so
n0.8-18454-g9d602a0