Make doased program to inherit user's class limits.
On FreeBSD limits set by the user's class (in /etc/login.conf) would
not be respected when running doas. The default class would always
be used, ignoring both the classing class and the target user's class.
This came about because FreeBSD has a "class" field in the password
structure, but other supported systems like Linux do not. doas.c and
env.c have been patched to support FreeBSD's class field in the password
structure. Login class limits are now respected.
Borrowed from slicer69's commit
ab3ae5ad412a135bab0f3c9201d695e09fabe3a8
from https://github.com/slicer69/doas.git repo.