Fix for broken ccArrayGetIndexOfObject

The optimisation introduced in 076f38c has broken ccArrayGetIndexOfObject which fails  now (i.e. returns CC_INVALID_INDEX) for object inside array but with indexes > 0. And it has nasty effect for all  CCTouchHandlers not unregistered and still handling events even if no longer existing... 

Here is a fix for that.

Regards
Jaro