[ArgPromote] Clean up a crash test case by rinsing it through opt,
renaming things to at least have somewhat spelled out names, and even
have meaningful names where I could guess at what they should be.

Also add FileCheck assertions that we're actually doing what we set out
to do for some of the tests, for example not promoting a type that would
result in infinite promotion.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294426 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed