[InstCombine] fold icmp with 'mul nsw/nuw' and constant operands

[InstCombine] fold icmp with 'mul nsw/nuw' and constant operands

This also removes a more specific fold that only handled icmp with 0.

https://rise4fun.com/Alive/sdM9

  Name: mul nsw with icmp eq
  Pre: (C1 != 0) && (C2 % C1) == 0
  %a = mul nsw i8 %x, C1
  %r = icmp eq i8 %a, C2
    =>
  %r = icmp eq i8 %x, C2 / C1

  Name: mul nuw with icmp eq
  Pre: (C1 != 0) && (C2 %u C1) == 0
  %a = mul nuw i8 %x, C1
  %r = icmp eq i8 %a, C2
    =>
  %r = icmp eq i8 %x, C2 /u C1

  Name: mul nsw with icmp ne
  Pre: (C1 != 0) && (C2 % C1) == 0
  %a = mul nsw i8 %x, C1
  %r = icmp ne i8 %a, C2
    =>
  %r = icmp ne i8 %x, C2 / C1

  Name: mul nuw with icmp ne
  Pre: (C1 != 0) && (C2 %u C1) == 0
  %a = mul nuw i8 %x, C1
  %r = icmp ne i8 %a, C2
    =>
  %r = icmp ne i8 %x, C2 /u C1