Remove `system` to fix compiling error with iOS 11

Remove `system` to fix compiling error with iOS 11
0.0 0

#1

Before cocos2d-x v3.16, CCFileUtils uses system() to remove a directory. iOS 11 remove system, so will cause compiling error with iOS 11. cocos2d-x v3.16 fixes this issue, and will be released about on Oct.9. The corresponding PR for this issue is here, you can apply this PR to fix it.


#2

#3

Thanks @zhangxm, that solve the problem


CCFileUtils.cpp Call to unavailable function 'system': not available on iOS