Enable KDC discovery through DNS URI records

Enable KDC discovery through DNS URI records

Add the dns_locate_server_uri(), locate_uri(), and parse_uri_fields()
functions to find and process KDC service information from specially
formatted URI records detailed at
http://k5wiki.kerberos.org/wiki/Projects/KDC_Discovery

Search for URI records before searching for SRV records.  Rename
dns_locate_server() to dns_locate_server_srv() for consistency.  Add
URI-specific information to the t_locate_kdc host entry output.

ticket: 8496