Fix handling of TAT sending failures

dns_view_zonecut() may associate the dns_rdataset_t structure passed to
it even if it returns a result different then ISC_R_SUCCESS.  Not
handling this properly may cause a reference leak.  Fix by ensuring
'nameservers' is cleaned up in all relevant failure modes.

(cherry picked from commit 8666f8d2)
13 jobs for 423-fix-handling-of-tat-sending-failures-v9_12 in 8 minutes and 8 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Precheck
passed #25690
amd64 docker linux
precheck:debian:sid:amd64

00:00:12

 
  Build
passed #25691
amd64 docker linux
build:centos:centos6:amd64

00:02:42

passed #25692
amd64 docker linux
build:centos:centos7:amd64

00:02:53

passed #25693
amd64 docker linux
build:debian:sid:amd64

00:02:06

passed #25694
i386 docker linux
build:debian:sid:i386

00:02:12

 
  Test
passed #25699
amd64 docker linux
systemtest:centos:centos6:amd64

00:04:52

passed #25700
amd64 docker linux
systemtest:centos:centos7:amd64

00:04:52

passed #25701
amd64 docker linux
systemtest:debian:sid:amd64

00:04:53

passed #25702
i386 docker linux
systemtest:debian:sid:i386

00:05:01

passed #25695
amd64 docker linux
unittest:centos:centos6:amd64

00:01:03

passed #25696
amd64 docker linux
unittest:centos:centos7:amd64

00:01:05

passed #25697
amd64 docker linux
unittest:debian:sid:amd64

00:01:04

passed #25698
i386 docker linux
unittest:debian:sid:i386

00:01:06