[lldb][Process/FreeBSDKernelCore] Add ppc64le support (#180669)
This is LLDB version of
https://cgit.freebsd.org/ports/tree/devel/gdb/files/kgdb/ppcfbsd-kern.c.
This enables selecting ppc64le and reading registers from PCB structure
on core dump and live kernel debugging. FPU registers aren't supported
yet due to pcb structure issue, but this change still achieves feature
parity with KGDB. Trapframe unwinding support will be implemented in
future. Test files using core dump from ppc64le will be implemented once
other kernel debugging improvements are done.
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Signed-off-by: Minsoo Choo <minsoochoo0122@proton.me>