Solve the crash in CocoStudioComponentsTest.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into develop
Merge pull request #5573 from natural-law/develop

Solve the crash in CocoStudioComponentsTest.
Solve the crash in WebSocketTest when the network in disconnected.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into develop
Merge pull request #5589 from natural-law/develop

Solve the crash in WebSocketTest when the network in disconnected.
check validation of ndk_root
Merge pull request #5594 from minggo/install

check validation of ndk_root