Log Message:
x265: updated to 2.7

Version 2.7

New features
1. :option:--gop-lookahead can be used to extend the gop boundary(set by \ 
--keyint). The GOP will be extended, if a scene-cut frame is found within this \ 
many number of frames.
2. Support for RADL pictures added in x265.
   :option:--radl can be used to decide number of RADL pictures preceding the \ 
IDR picture.

Encoder enhancements
1. Moved from YASM to NASM assembler. Supports NASM assembler version 2.13 and \ 
greater.
2. Enable analysis save and load in a single run. Introduces two new cli options \ 
--analysis-save <filename> and --analysis-load <filename>.
3. Comply to HDR10+ LLC specification.
4. Reduced x265 build time by more than 50% by re-factoring ipfilter.asm.

Bug fixes
1. Fixed inconsistent output issue in deblock filter and --const-vbv.
2. Fixed Mac OS build warnings.
3. Fixed inconsistency in pass-2 when weightp and cutree are enabled.
4. Fixed deadlock issue due to dropping of BREF frames, while forcing slice \ 
types through qp file.