Remove a test that was only testing for physreg joining.

Remove a test that was only testing for physreg joining.

This is the same as the other tests: Clever tricks are required to make
the arguments and return value line up in a single-instruction function.
It rarely happens in real life.

We have plenty other examples of this behavior.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157030 91177308-0d34-0410-b5e6-96231b3b80d8