MFC 303109: Update crashinfo to work with newer gdb from ports.

If gdb from ports is installed, use it instead of the base system gdb
to extract variables from a kernel. Note that base gdb and ports gdb
do not support the same options for invoking a single command in batch
mode, so a wrapper shell function is used. In addition, prefer kgdb
from ports when generating a backtrace if present.

PR: 193335

Merged /head:r256510,256512,257376,257469,260052:

Make 'netstat -i' use getifaddrs(3) instead of kvm(3).

MFC r259870:

Do not truncate the ``command'' column in ``ps'' output.

Merged /head:r256510,256512,257376,257469,260052:

Make 'netstat -i' use getifaddrs(3) instead of kvm(3).

MFC r259870:

Do not truncate the ``command'' column in ``ps'' output.