Include the complete list of threads of all running processes
in the FreeBSDKernel plugin.  This makes it possible to inspect
the states (including partial register dumps from PCB) of all kernel
and userspace threads at the time of crash, or at the time of reading
/dev/mem first.

Differential Revision: https://reviews.llvm.org/D116255

Introduce a FreeBSDKernel plugin that provides the ability to read
FreeBSD kernel core dumps.  The plugin utilizes libfbsdvmcore to provide
support for both "full memory dump" and minidump formats across variety
of architectures supported by FreeBSD.  It provides the ability to read
kernel memory, as well as the crashed thread status with registers
on arm64, i386 and x86_64.

Differential Revision: https://reviews.llvm.org/D114911

This reverts commit aedb328a4dc9cb48ee3cf3198281649ea2c4f532.
I have failed to make the new tests conditional to the presence
of libfbsdvmcore.

Introduce a FreeBSDKernel plugin that provides the ability to read
FreeBSD kernel core dumps.  The plugin utilizes libfbsdvmcore to provide
support for both "full memory dump" and minidump formats across variety
of architectures supported by FreeBSD.  It provides the ability to read
kernel memory, as well as the crashed thread status with registers
on arm64, i386 and x86_64.

Differential Revision: https://reviews.llvm.org/D114911