Reland rG4fcd1a8e6528:[llvm-exegesis] Add option to check the hardware...

Reland  rG4fcd1a8e6528:[llvm-exegesis] Add option to check the hardware support for a given feature before benchmarking.

This is mostly for the benefit of the LBR latency mode.
Right now, it performs no checking. If this is run on non-supported hardware, it will produce all zeroes for latency.

      Differential Revision: https://reviews.llvm.org/D85254

New change: Updated lit.local.cfg to use pass the right argument to llvm-exegesis to actually request the LBR mode.

Differential Revision: https://reviews.llvm.org/D88670