Fix compile error for Window 8.
Fix compile error for Window 8.

haithemaraissia/CocosSharp,MSylvia/CocosSharp,zmaruo/CocosSharp,hig-ag/CocosSharp,MSylvia/CocosSharp,zmaruo/CocosSharp,hig-ag/CocosSharp,haithemaraissia/CocosSharp,mono/CocosSharp,TukekeSoft/CocosSharp,TukekeSoft/CocosSharp,mono/CocosSharp