libvpx

Removing 'new' probability calculation from convert_distribution().

We don't have to calculate 'new' probability in convert_distribution()
because it is enough to calculate only 'new' counters which could be used
to calculate probability if necessary. That's why removing a lot of unused
temporary probability arrays and reducing number of get_binary_prob()
calls.

Change-Id: I4e14eb7203d1ace61bbddefd6b9b6326be83ba63