Some optimizations on integer affine estimation

1. Adds a limit on number of candidate samples used for the
estimation.
2. Adds a limit on max mv magnitude for use in the least-squares
3. Makes some of the internal variables 32-bit.

Impact on coding efficiency in the noise range.

Change-Id: I8c1c3216368ceb2e3548660a3b8c159df54a8312
3 files changed