arch-arm: Add support for Tarmac trace generation

arch-arm: Add support for Tarmac trace generation

This patch introduces the TarmacTracer: an instruction tracer which
allows to dump a gem5 execution trace in Tarmac format [1]. The new
tracer is supporting either Tarmac and TarmacV8 format specifications.
Not every traceable information has been implemented:

Implemented Trace Type:
    Instruction Trace
    Register Trace
    Processor Memory Access Trace

Unimplemented Trace Type:
    Program Flow Trace
    Event Trace
    Memory Bus Trace

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

Change-Id: I8799d8e5852e868673f728971db3fe8c63961f5e
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9382
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>