Add Sad arm64 code
Add gnu assembler support.
Refine some code
simplify stash pop bs
fix a bug that if..else are grouped incorrectly
Merge pull request #900 from ruil2/enc_warnings

fix a bug that if..else are grouped incorrectly
Merge pull request #898 from ruil2/enc_rc_4

simplify stash pop bs
remove macro NO_WAITING_AU for always on
Merge pull request #902 from huili2/remove_No_Waiting_Au

remove macro NO_WAITING_AU for always on
Merge pull request #903 from zhilwang/arm64-sad

Add Arm64 sad code
Merge branch 'master' of github.com:cisco/openh264 into ParallelTest