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 f4b403e8)
13 jobs for 423-fix-handling-of-tat-sending-failures-v9_11 in 8 minutes and 2 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Precheck
passed #25703
amd64 docker linux
precheck:debian:sid:amd64

00:00:14

 
  Build
passed #25704
amd64 docker linux
build:centos:centos6:amd64

00:02:41

passed #25705
amd64 docker linux
build:centos:centos7:amd64

00:02:50

passed #25706
amd64 docker linux
build:debian:sid:amd64

00:02:08

passed #25707
i386 docker linux
build:debian:sid:i386

00:02:13

 
  Test
passed #25712
amd64 docker linux
systemtest:centos:centos6:amd64

00:04:37

passed #25713
amd64 docker linux
systemtest:centos:centos7:amd64

00:04:45

passed #25714
amd64 docker linux
systemtest:debian:sid:amd64

00:04:42

passed #25715
i386 docker linux
systemtest:debian:sid:i386

00:04:55

passed #25708
amd64 docker linux
unittest:centos:centos6:amd64

00:01:06

passed #25709
amd64 docker linux
unittest:centos:centos7:amd64

00:01:22

passed #25710
amd64 docker linux
unittest:debian:sid:amd64

00:01:18

passed #25711
i386 docker linux
unittest:debian:sid:i386

00:01:05