[SPARC] Switch to the Machine Scheduler.

The (mostly-deprecated) SelectionDAG-based ILPListDAGScheduler scheduler
was making poor scheduling decisions, causing high register pressure and
extraneous register spills.

Switching to the newer machine scheduler generates better code -- even
without there being a machine model defined for SPARC yet.

(Actually committing the test changes too, this time, unlike r247315)

llvm-svn: 247343