on the same order as the sse2 fast quantize change: ~2%
except for 32bit. only a slight improvment there.
Change-Id: Iff80e5f1ce7e646eebfdc8871405458ff911986b
(test clip: tulip)
For good quality mode with speed=1, this gave the encoder
a small (2 - 3%) performance boost.
Change-Id: I8a1d4269465944ac0819986c2f0be4b0a2ee0b35