MFC r285253 (hrs):

• Add IPv6 support in quota(1). While rpc.rquotad has supported PF_INET6 for a long time, quota(1) utility supported only PF_INET.
• Clean up confusing changes in f_mntfromname.
• Add an entry for rquotad with rpc/udp6 to inetd.conf.

PR: 194084
Sponsored by: The FreeBSD Foundation