[PATCH 5/8] gdb/riscv: introduce bare metal core dump support

[Paul Mathieu]

Thanks Luis for getting the ball rolling again!

As far as I'm concerned, I haven't deployed much infrastructure to
generate or otherwise deal with bare metal cores at the moment, so I'm
happy to work with anything. The one thing that is a big deal to me is
support for RTOS threads.

ELF + NOTES seems like the obvious choice to me, as it matches what
I'm used to. Most online resources about core dumps seem to be
specifically about Linux core dumps, so it would be less surprising
and more helpful to share as much as possible with it, IMO.

What I'm expecting from a bare metal core dump:
- memory dump sections
- CPU registers
- when available (RTOS support from the dumping side): inactive
threads' CPU registers