This commit replaces an integer divide with a table-lookup. It is
to improve decoding speed, and at the same time, to reduce possible
complications with a bug in AMD Family 12h processors:
"665 Integer Divide Instruction May Cause Unpredictable Behavior"
Change-Id: I678b707a538798a923850bac467e66e847e6def7
This commit turns on the existing vp9_get_prob function using
64 bit in the intermediate step. It fixes the ioc issue for 4K
above frame sizes (issue 828).
Change-Id: I9f627f3beca2c522f73b38fd2a3e7eefdff01a7c