Fix intra-refresh + hrd
ICL/MSVS: Fix shared library generation and usage
MSVS requires exported variables to be declared with the DATA keyword, and requires that imported variables be declared with dllimport.
This does not fix x264 cli being unable to use a shared library built by ICL however.
configure: correct use of RC variable and add --extra-rcflags
Update config.guess and config.sub
Adds support for a bunch of targets, including:
aarch64 (armv8)
arm-linux-androideabi
configure: force select -mXX gcc option for i386/x86-64
Makes multilib compilation more convenient.
Fix disabling of mbtree when using 2pass encoding and zones
Eradicate all mention of Extended Profile
x264 never supported it and never will because nobody uses it.
Add Level 5.2 support
Faster chroma weight cost calculation

New assembly function with SSE2, SSSE3 and XOP implementations for calculating absolute sum of differences.
Add mb_info API for signalling constant macroblocks
Some use-cases of x264 involve encoding video with large constant areas of the frame.
Sometimes, the caller knows which areas these are, and can tell x264.
This API lets the caller do this and adds internal tracking of modifications to macroblocks to avoid problems.
This is really only suitable without B-frames.
An example use-case would be using x264 for VNC.
Fix some bugs in mb_info code
Add support for RGB formats in bit-depth conversion filter
Threaded lookahead

Split each lookahead frame analysis call into multiple threads.  Has a small
impact on quality, but does not seem to be consistently any worse.

This helps alleviate bottlenecks with many cores and frame threads. In many
case, this massively increases performance on many-core systems.  For example,
over 100% faster 1080p encoding with --preset veryfast on a 12-core i7 system.
Realtime 1080p30 at --preset slow should now be feasible on real systems.

For sliced-threads, this patch should be faster regardless of settings (~10%).

By default, lookahead threads are 1/6 of regular threads.  This isn't exacting,
but it seems to work well for all presets on real systems.  With sliced-threads,
it's the same as the number of encoding threads.
Fix crash with --fps 0
Fix some integer overflows and check input parameters better.
Also fix incorrect type specifiers for demuxer info printing.
x86inc: import patches from libav
Allow manual invocation of WIN64_SPILL_XMM even under INIT_MMX
SSE version of mova is movaps rather than movdqa.
YMM version of movnta.
Add mp size for named arguments.
Fix DEFINE_ARGS when used outside of a cglobal.
Define a few more cpuflags.
3-argument wrappers for a few more instructions.
Cap ratecontrol predictor parameters
Limits VBV mispredictions after long periods of relatively constant video.
Print elapsed time in encoding progress indicator
Support changing resolutions between passes with macroblock-tree
Implement a basic separable bilinear filter to rescale the quantizer offsets.
Structure inspired by swscale, but floating-point instead of fixed-point.
Not as optimized as it could be, but it's quite fast already.

Example compression penalties on a 720p video game recording:
First pass with 720p and second as 480p: ~-1.5% (vs. same res)
First pass with 480p and second as 720p: ~-3% (vs. same res)
Try 8x8 transform analysis even when sub8x8 partitions are present
Turn off the sub8x8 partitions, try it, and turn them back on if it didn't help.
Small compression improvement with p4x4 on (~0.1-0.5%).
Also update related comments.
Faster predictor checking with subme<3
Fix a typo that made an early-skip less effective.
Avoid a relatively unpredictable branch.
Slightly changed output due to the typo-fix.
~50 cycles faster on Core i7.