[InstCombine] add 'exact' variants of all tests; NFC

We can likely remove most of these as redundant in the near future, 
but I'm trying to make sure I don't introduce any regressions with D38514.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314907 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed