Issue #4277: fixed a bug of ControlButton that it will crash when it deletes itself in its callback.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into Iss4277_fixedControlButtonBug
Merge pull request #5744 from dingpinglv/Iss4277_fixedControlButtonBug

Issue #4277: fixed a bug of ControlButton that it will crash when it deletes itself in its callback.