Add "-n" flag to sockstat.

sockstat can "hang" on getpwuid() calls in situations when FreeBSD
is joined to a directory service (AD/LDAP etc) and the directory
service fail to answer in a timely manner when trying to resolve
numeric UIDs to user names.

Submitted by: Caleb St. John <caleb@ixsystems.com>
MFC after: 1 week