Added highbitdepth sse2 acceleration for quantize

Also includes block error.

(This patch is mostly cherry picked from
commit db7192e0b014a331a1dcb102c8a1148e9f0e1081)

Change-Id: Idef18f90b111a0d0c9546543d3347e551908fd78
Fix some minor nits.

Change-Id: Ib8810d431fa20a2c78e0caaa28eb2c99903e60fb
Merge "Added highbitdepth sse2 acceleration for quantize"
Merge "Fix some minor nits."