arch: Stop using TheISA within the ISAs.

We know for sure what the ISA is, so there's no need for the
indirection.

Change-Id: I73ff04c50890d40a4c7f40caeee746b68b846cb3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18488
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Add support for Tarmac trace-based simulation

A new InstTracer (TarmacParser) has been implemented. This tracer is
parsing a pre-existing Tarmac trace file [1] while gem5 is running; it
is comparing execution data together with trace data and it is dumping
differences.
This allows to use Tarmac format as a glue between heterogeneous
simuators speaking the same Tarmac language.

Kudos to Giacomo Gabrielli for writing the original tracer.

[1]: https://developer.arm.com/docs/dui0845/f/tarmac-trace-file-format

Change-Id: I9b92204a149813166166adba4a7c61a248bdcac3
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9381
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>