[X86][BtVer2] Added Jaguar cpu cycle counter to permit llvm-exegesis latency testing

Ideally we'd be able to test a CPU by using __builtin_readcyclecounter()/RDTSC instead (PR37193) if a model/cycle-counter is not specified.

NOTE: Jaguar PMCs don't give good coverage of resource pipes specified in the model (at the macro-vs-micro-op levels) but we should be able to cover at least a few resources.
llvm-svn: 333190