Update test case to be compatible with auto-migration to new getelementptr...

Update test case to be compatible with auto-migration to new getelementptr syntax coming in the near future

The first change won't touch GEPOperators such as these, but the update
script only identifies them by the leading '(' after getelementptr or
'getelementptr inbounds', so update this test to at least have those
features to allow auto-migrating.

llvm-svn: 229198