[InstCombine] add tests for select to logic folds; NFC

As discussed in D45862, we want these folds sometimes
because they're good improvements.
But as we can see here, the current logic doesn't
check uses and doesn't produce optimal code in all
cases. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330837 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed