[InstCombine] Teach foldOrOfICmps to allow icmp eq MIN_INT/MAX to be part of a...

[InstCombine] Teach foldOrOfICmps to allow icmp eq MIN_INT/MAX to be part of a range comparision. Similar for foldAndOfICmps

We can treat icmp eq X, MIN_UINT as icmp ule X, MIN_UINT and allow
it to merge with icmp ugt X, C. Similar for the other constants.

We can do simliar for icmp ne X, (U)INT_MIN/MAX in foldAndOfICmps. And we already handled UINT_MIN there.

Fixes PR42691.

Differential Revision: https://reviews.llvm.org/D65017

llvm-svn: 366945