Update net-svc to work for an exclusive-IP DHCP zone as it does for global, and wait a few seconds for DHCP results
For a DHCP global zone, net-svc (svc:/network/service:default) creates/updates resolv.conf to incorporate DHCP DNSserv and DNSdmain parameter values and updates nsswitch.conf to ensure dns is set as an active database for hosts/ipnodes.
net-svc does nothing for a non-global, exclusive-IP DHCP zone, but it could do easily the same convenient updating of resolv.conf/nsswitch.conf.
Also, net-svc only tries once to fetch DNSserv and DNSdmain from dhcpagent (dhcpinfo), which generally works for a global zone. For fast-booting non-global zones, there needs to be a few seconds allowance — so update to check once per second up to six seconds.