modify WELS_CLIP1 to be inline functions
remove unncessary cast
add scene change detector for further extension
remove black space at lineend
Rename the asm subdirectories to x86

This is consistent with having the arm assembly in a subdirectory
called arm.
Use __APPLE__ instead of APPLE_IOS for using the apple cpu feature detection
Use __APPLE__ instead of APPLE_IOS in the arm assembly sources
Merge pull request #532 from huili2/WELS_CLIP1

Modify MACRO WELS_CLIP1 as inline functions
Merge pull request #537 from mstorsjo/rename-x86-asm

Rename the asm subdirectories to x86
Merge pull request #538 from mstorsjo/use-apple-builtin-define

Use __APPLE__ instead of APPLE_IOS for apple/arm specific features
reoranize common to inc/src/x86/arm
add missing build files
Merge pull request #540 from licaiguo/reorgcommon-pr

reorganize common to inc/src/x86/arm
Merge pull request #535 from volvet/add-scene-change-detector

Add scene change detector