parameters:
External library support:
--disable-avs disable avisynth support
--disable-swscale disable swscale support
--disable-lavf disable libavformat support
--disable-ffms disable ffmpegsource support
--disable-gpac disable gpac support
There have no ffmpeg or libav when build x264, so no needed
these parameters.
Signed-off-by: Steven Liu <lingjiujianke@gmail.com>