[InstCombine] Add new rule for MIN(MAX(~A, ~B), ~C) et. al.

Summary:
Optimizing these well are especially interesting for IRCE since it
"clamps" values by generating this sort of pattern through SCEV
expressions.

Depends on D9352.

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9353

llvm-svn: 236203