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.
Revert r2204
People don't seem to like this so I'm just going to get rid of it.
Free user supplied data when deleting a frame
This eliminates a memory leak when calling x264_encoder_close.
x86inc: automatically insert vzeroupper for YMM functions
Backported from libav.
Remove special-casing for OpenBSD pthread handling
Previously it was policy to use -pthread, but OpenBSD now recommends -lpthread.
its been libpthread anyway and policy has changed to stop using -pthread.
Export the average effective CRF of each frame
Useful to judge the resulting quality of a frame when VBV is enabled.
Improve mb_info constant mb optimization
Allow fast skipping even if the pskip MV isn't zero.
Enhance nalu_process
Add the input frame opaque pointer to the arguments.
This makes it easier to use with multiple simultaneous x264 encodes.
Fix mb_info_free with sliced threads
x264 would free mb_info before it was completely done using it.
Enhance mb_info: add mb_info_update
This feature lets the callee know which decoded macroblocks have changed.
Set libm in the configure script if the OS has libm
Prerequisite for another configure patch after this.
Idea copied from libpthread.
Fix pkg-config for dynamic vs static linking
Fix use of deprecated av_close_input_file call
Fix ALIGNED_ARRAY_EMU macros on ICL
ICL's preprocessor doesn't handle it correctly.
This fix is similar to libav's fix in 0db2d9.
Fix reconfiguring to crf=0
Lossless mode can't currently be enabled mid-stream.