[InstCombine] clean up foldSelectICmpAnd(); NFC

As discussed in D45862, we want to delete parts of
this code because it can create more instructions
than it removes. But we also want to preserve some 
folds that are winners, so tidy up what's here to
make splitting the good from bad a bit easier.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330841 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed