Add a scheduling model for AMD 16H Jaguar (btver2).

This is a first pass at a scheduling model for Jaguar.
It's structured largely on the existing SandyBridge and SLM sched models.

Using this model, in addition to turning on the PostRA scheduler, results in
some perf wins on internal and 3rd party benchmarks. There's not much difference
in LLVM's test-suite benchmarking subset of tests.

Differential Revision: http://reviews.llvm.org/D5229