Fixed compilation errors when disabling CC_ENABLE_STACKABLE_ACTION
Merge pull request #6350 from natural-law/develop

Update the reference of submodule plugin-x.
Merge pull request #6349 from dumganhar/config-fix

Fixed compilation errors when disabling CC_ENABLE_STACKABLE_ACTION
Merge pull request #6351 from natural-law/develop

Add tip message in setup.py for prompt the usage of some environment var...
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into develop

Conflicts:
	cocos/2d/CCActionInterval.cpp