Add optimizations for icmp eq/ne (mul(X, Y), 0)

1. Add checks if X and/or Y are odd. The Odd values are unnecessary to
   the icmp: isZero(Odd * N) == isZero(N)

2. If neither X nor Y is known odd, then if X * Y cannot overflow AND
   if X and/or Y is non-zero, the non-zero values are unnecessary to the
   icmp.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D140850