dnsserver: Add support for dns wildcards

dnsserver: Add support for dns wildcards

Add support for dns wildcard records. i.e. if the following records
exist

  exact.samba.example.com 3600 A 1.1.1.1
  *.samba.example.com     3600 A 1.1.1.2

look up on exact.samba.example.com will return 1.1.1.1
look up on *.samba.example.com     will return 1.1.1.2
look up on other.samba.example.com will return 1.1.1.2

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
BUG: https://bugzilla.samba.org/show_bug.cgi?id=12952