release: Allow sudo -g anyone and sudo -u anyone -g anytwo

When only the user (ALL) is specified explicitly, and the group is
implied, only sudo -u works. Specifying both the user and group, like
(ALL:ALL), is required to:

1. Use sudo -g by itself (with no -u user)
2. Use sudo -u and -g together, with a -g group that is different from the -u user's primary group

Obtained from: https://github.com/sudo-project/sudo/commit/1d13533ea3cda05ec666c45c6c533b614fdd97aa
Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/835