Fixed #5781: update the build.xml for v3.0 rc2
Merge branch 'develop' of git://github.com/cocos2d/cocos2d-html5 into Iss5781_ReleaseV3rc2
Merge pull request #2075 from dingpinglv/Iss5781_ReleaseV3rc2

Fixed #5781: update the build.xml for v3.0 rc2