Move recognition of rotate-right operations to the
MachineOperatorReducer, so we don't need to repeat that in the
InstructionSelector for every backend.

TEST=base-unittests,compiler-unittests,cctests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/469213002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23121 ce2b1a6d-e550-0410-aec6-3dcde31c8c00