Bug fix cc scheduler blocked element

Previous PR https://github.com/cocos2d/cocos2d-x/pull/5732

----
Example

We scheduled teget for example method update

void MyObject::update(float dt)
{
//Here CCScheduler::m_bUpdateHashLocked is set to true
//Also here scheduler for LeafAnimator::getInstance() is
paused!

CCDirector::sharedDirector()->getScheduler()->unscheduleUpdateForTarget(&LeafAnimator::getInstance()
);

CCDirector::sharedDirector()->getScheduler()->scheduleUpdateForTarget
(&LeafAnimator::getInstance(), INT_MAX, false );
//So when we want reschedule paused field isn't updated. Priority also
but this is in todo :)
}