devel/gdb: Update to 12.1.

[jhb]

Summary

One notable feature included in 12.1 is async target support
permitting the use of commands like continue&. In addition, this
commit backports various post-12 commits to add support for hardware
breakpoints/watchpoints on aarch64 as well as support for resolving
TLS variables from core dumps on amd64 and i386 via the recently added
NT_X86_SEGBASES core dump note.

[jhb]

devel/gdb/Makefile

126

Clang on HEAD at least doesn't include this option so having this here was spamming the build log with lots of complaints about the option being unknown.

devel/gdb/files/patch-gdb_amd64-bsd-nat.c

1

This patch is a lot harder to do now as I have refactored the register fetching upstream to permit seeing all of the segment registers on x86. I'm also not sure this fixes a real issue that can happen in normal practice. GDB shouldn't be trying to alter rflags unless a user has explicitly tried to set $rflags and we'd rather report an error to the user in that case than silently ignore the change to $rflags.

[jhb]

• Added arm/arm64 TLS patches merged to gdb master today.

[pizzamig]

LGTM!