Optimize easy multiply and easy div remainder.

Update OpRegRegShift and OpRegRegRegShift to use RegStorage parameters.
Add special cases for *0 and *1. Add more easy multiply special cases for
Arm.
Reuse easy multiply in SmallLiteralDivRem() to support remainder cases.

Change-Id: Icd76a993d3ac8d4988e9653c19eab4efca14fad0
9 files changed