Update port to GDB 8.3.
New features in GDB 8.3 include support for DWARF index caches and
styling (colors) in the CLI and TUI. Source code styling is also
available via the new SOURCE_HIGHLIGHT option (enabled by default).
GDB 8.3 also adds support for FreeBSD/riscv64.
In addition, kgdb has been updated for changes in 8.3 along with
support for FreeBSD/riscv64 kernels.
The libc++ helpers have been updated to a newer version which adds
support for std::list<> and std::forward_list<>. The helpers now
also support Python 3.
Finally, a few post-8.3 patches have been backported which add suport
for TLS (Thread Local Storage) variables on FreeBSD amd64, i386,
powerpc, and riscv architectures. Note that amd64 and i386 do not
support examining TLS variables in core dumps currently. This support
along with support for additional architectures require kernel changes
and will be added in the future once the kernel has been updated.
Reviewed by: pizzamig (maintainer)
Differential Revision: https://reviews.freebsd.org/D20403