Tidy up this test more:

1) Make the checked assertions a bit more precise. We really want the
   canonical forms coming out of reassociate to be exactly what is
   expected.
2) Remove other passes, and switch the test to actually directly check
   that reassociate makes the important transforms and
   canonicalizations.
3) Fold in a related test case now that we're using FileCheck. Make the
   same tidying changes to it.

llvm-svn: 155311