[InstCombine] Add test cases demonstrating failure to handle (select (icmp eq (and...

[InstCombine] Add test cases demonstrating failure to handle (select (icmp eq (and X, C1), 0), Y, (or Y, C2)) when the icmp portion gets turned into a truncate and a signed compare with 0.

InstCombine has an optimization that recognizes an and with the sign bit of legal type size and turns it into a truncate and compare that checks the sign bit. But the select handling code doesn't recognize this idiom.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305338 91177308-0d34-0410-b5e6-96231b3b80d8