[InstCombine] Provide more test cases for cast-folding [NFC]

Summary: In r275989 we enabled the folding of `logic(cast(icmp), cast(icmp))` to `cast(logic(icmp, icmp))`. Here we add more test cases to assure this folding works for all logical operations `and`/`or`/`xor`.

Reviewers: grosser

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22561

Contributed-by: Matthias Reisinger
llvm-svn: 276105