[amd64] Fast OP_LREM_IMM for power of two operands.

This was the reason for one of our bad performance results in the
paper "Clash of the Lambdas" by Biboudis, Palladinos, Smaragdakis:

http://cgi.di.uoa.gr/~biboudis/clashofthelambdas.pdf

There's clearly way more we could do in this regard.  More specifically
with other number types (unsigned longs, unsigned ints, ...), more
generally for more immediate operands to the division (integer divisions
with constant divisor can always be implemented via multiplication - the
CLR does this for the few cases I tested) and for more architectures.
How deep down the rabbit hole do we want to go?
target specific check, we should be reducing those in method-to-ir.c and not the other way around.