Revert "ffmpeg: Do not build encoders and muxers."

This reverts commit 8b96f6ccc88a8519d071f61394081c7ccec221d9.

It does not help final size of mpv.exe so much.
mpv: Remove the temp fix to ao_wasapi0
mpv: Removed the patch for VCD on Win32
Enable libavresample otherwise mplayer2 will not work properly
Moved to cygwin64
Added tasks/harfbuzz-build in order to build harfbuzz without gtkdoc