[LoopUnroll] Make the test for PR33437 actually useful.
[LoopUnroll] Make the test for PR33437 actually useful.

I forgot to specify -unroll-loop-peel, making this test not
really effective. While here, adjust some details (naming and
run line). Thanks to Sanjoy and Michael Z. for pointing out in
their post-commit reviews.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@312015 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm