[ValueTracking] enhance matching of umin/umax with 'not' operands

The cmyk test is based on the known regression that resulted from:
rGf2fbdf76

This improves on the equivalent signed min/max change:
rG867f0c3c

The underlying icmp equivalence is:
  ~X pred ~Y --> Y pred X

For an icmp with constant, canonicalization results in a swapped pred:
  ~X < C -->  X > ~C