Fix nacl build after merge from upstream master.

CCFileUtils is now split into generic and platform
sources.

tinyxml2 is now part of the main cocos lib.

webp library is now a dependency.

Moved common include paths to cocos2dx.mk.

BUG=None

Committed: https://github.com/sbc100/cocos2d-x/commit/96fe0f1

Review URL: https://codereview.chromium.org/12326088