Optimize rem-int/lit too.

Bryan hitting the bug in my div-int/lit optimization (that caused it to
try to rewrite rem-int/lit too) shows that I was wrong in assuming % wasn't
worth doing because it wouldn't be hot enough.

Before:

                     benchmark  ns logarithmic runtime
       RemainderIntByConstant2  44 XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
    RemainderIntByConstant2048  34 XXXXXXXXXXXXXXXXXXXXXX|||||
       RemainderIntByConstant8  44 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
       RemainderIntByVariable2  40 XXXXXXXXXXXXXXXXXXXXXXXXXXX||

After:

                     benchmark  ns logarithmic runtime
       RemainderIntByConstant2  13 XXXXXXXXX|||||||||||
    RemainderIntByConstant2048  16 XXXXXXXXXXXX||||||||||
       RemainderIntByConstant8  16 XXXXXXXXXXXX||||||||||
       RemainderIntByVariable2  40 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Bug: 2614702
Change-Id: I719fc8765feececd5b73c3cb2e44dd3cf20c45ce