plugin/proxy: https_google does not support NAPTR

[miekg]

For some reaon the proxy plugin does not support NAPTR records, although google does:
https://dns.google.com/resolve?name=mplus.ims.vodafone.com.&type=naptr

{"Status": 0,"TC": false,"RD": true,"RA": true,"AD": false,"CD": false,"Question":[ {"name": "mplus.ims.vodafone.com.","type": 35}],"Answer":[ {"name": "mplus.ims.vodafone.com.","type": 35,"TTL": 1966,"data": "10 100 S SIP+D2U  _sip._udp.mplus.ims.vodafone.com."},{"name": "mplus.ims.vodafone.com.","type": 35,"TTL": 1966,"data": "10 100 S SIP+D2T  _sip._tcp.mplus.ims.vodafone.com."},{"name": "mplus.ims.vodafone.com.","type": 35,"TTL": 1966,"data": "10 100 S SIPS+D2T  _sips._tcp.mplus.ims.vodafone.com."}]}

something, something, json?

[miekg]

Logs as:

Nov 14 08:10:40 raspberrypi coredns[7925]: 192.168.1.124 - [14/Nov/2017:08:10:40 +0000] "NAPTR IN mplus.ims.vodafone.com. udp 40 false 512" SERVFAIL qr,rd 40 79.988891ms
Nov 14 08:10:40 raspberrypi coredns[7925]: 14/Nov/2017:08:10:40 +0000 [ERROR 0 mplus.ims.vodafone.com. NAPTR] unreachable backend: no upstream host

[miekg]

duplicate of #1233