Skip some system tests if perl-net-dns library is not available

Fixup for 978c7b2e, MR !985.

WIP: I would argue that this approach is dangerous because it completely
hides tests with missing depedencies from test suite output. Maybe we
should conditionally generate prereq.sh which would just exit 77 to
indicate a missing depedency?
76 jobs for !4528 with pspacek/test-fixes in 17 minutes and 48 seconds (queued for 8 seconds)
latest detached
Status Job ID Name Coverage
  Autoconf
passed #1388334
amd64 linux
autoreconf

00:00:18

 
  Precheck
passed #1388336
amd64 linux
clang-format

00:00:18

passed #1388337
amd64 linux
coccinelle

00:03:36

failed #1388338
amd64 linux
danger

00:00:15

passed #1388335
amd64 linux
misc

00:00:21

passed #1388339
amd64 linux
tarball-create

00:01:36

 
  Build
passed #1388352
amd64 linux
clang:asan

00:02:03

passed #1388356
amd64 linux
clang:buster:amd64

00:01:09

passed #1388359
amd64 libvirt
clang:freebsd11:amd64

00:01:05

passed #1388360
amd64 libvirt
clang:freebsd12:amd64

00:01:04

passed #1388361
amd64 libvirt
clang:openbsd:amd64

00:02:25

passed #1388354
amd64 linux
clang:tsan

00:01:11

passed #1388340
amd64 linux
gcc:alpine3.12:amd64

00:01:02

passed #1388351
amd64 linux
gcc:asan

00:01:39

passed #1388344
amd64 linux
gcc:buster:amd64

00:00:53

passed #1388341
amd64 linux
gcc:centos7:amd64

00:00:58

passed #1388342
amd64 linux
gcc:centos8:amd64

00:01:02

passed #1388350
amd64 linux
gcc:focal:amd64

00:01:02

passed #1388355
amd64 linux
gcc:mutexatomics

00:00:56

passed #1388346
amd64 linux
gcc:out-of-tree

00:00:55

passed #1388345
amd64 linux
gcc:sid:amd64

00:01:01

passed #1388347
i386 linux
gcc:sid:i386

00:01:02

passed #1388357
amd64 linux
gcc:softhsm2.4

00:01:01

passed #1388358
amd64 linux
gcc:softhsm2.6

00:00:56

passed #1388343
amd64 linux
gcc:stretch:amd64

00:00:56

passed #1388353
amd64 linux
gcc:tsan

00:01:18

passed #1388348
amd64 linux
gcc:tumbleweed:amd64

00:01:00

passed #1388349
amd64 linux
gcc:xenial:amd64

00:01:05

passed #1388362
amd64 windows
msvc:windows:amd64

00:00:45

 
  Unit
passed #1388374
amd64 linux
unit:clang:asan

00:01:20

passed #1388378
amd64 linux
unit:clang:buster:amd64

00:01:07

passed #1388381
amd64 libvirt
unit:clang:freebsd11:amd64

00:01:38

passed #1388382
amd64 libvirt
unit:clang:freebsd12:amd64

00:01:32

passed #1388383
amd64 libvirt
unit:clang:openbsd:amd64

00:02:47

passed #1388376
amd64 linux
unit:clang:tsan

00:03:05

passed #1388363
amd64 linux
unit:gcc:alpine3.12:amd64

00:01:09

passed #1388373
amd64 linux
unit:gcc:asan

00:01:18

passed #1388367
amd64 linux
unit:gcc:buster:amd64

00:02:08

passed #1388364
amd64 linux
unit:gcc:centos7:amd64

00:01:08

passed #1388365
amd64 linux
unit:gcc:centos8:amd64

00:01:10

passed #1388372
amd64 linux
unit:gcc:focal:amd64

00:01:06

passed #1388377
amd64 linux
unit:gcc:mutexatomics

00:01:08

passed #1388368
amd64 linux
unit:gcc:sid:amd64

00:01:06

passed #1388369
i386 linux
unit:gcc:sid:i386

00:01:12

passed #1388379
amd64 linux
unit:gcc:softhsm2.4

00:01:11

passed #1388380
amd64 linux
unit:gcc:softhsm2.6

00:01:07

passed #1388366
amd64 linux
unit:gcc:stretch:amd64

00:01:10

passed #1388375
amd64 linux
unit:gcc:tsan

00:03:55

passed #1388370
amd64 linux
unit:gcc:tumbleweed:amd64

00:01:06

passed #1388371
amd64 linux
unit:gcc:xenial:amd64

00:01:13

 
  System
passed #1388395
amd64 linux
system:clang:asan

00:13:13

passed #1388399
amd64 linux
system:clang:buster:amd64

00:11:38

failed #1388402
amd64 libvirt
system:clang:freebsd11:amd64

00:11:51

passed #1388403
amd64 libvirt
system:clang:freebsd12:amd64

00:11:51

passed #1388397
amd64 linux
system:clang:tsan

00:14:53

passed #1388384
amd64 linux
system:gcc:alpine3.12:amd64

00:12:24

passed #1388394
amd64 linux
system:gcc:asan

00:13:29

passed #1388388
amd64 linux
system:gcc:buster:amd64

00:13:03

passed #1388385
amd64 linux
system:gcc:centos7:amd64

00:11:52

passed #1388386
amd64 linux
system:gcc:centos8:amd64

00:12:22

failed #1388393
amd64 linux
system:gcc:focal:amd64

00:12:26

passed #1388398
amd64 linux
system:gcc:mutexatomics

00:11:53

passed #1388389
amd64 linux
system:gcc:sid:amd64

00:12:11

passed #1388390
i386 linux
system:gcc:sid:i386

00:11:40

passed #1388400
amd64 linux
system:gcc:softhsm2.4

00:11:49

passed #1388401
amd64 linux
system:gcc:softhsm2.6

00:12:32

passed #1388387
amd64 linux
system:gcc:stretch:amd64

00:11:47

passed #1388396
amd64 linux
system:gcc:tsan

00:15:17

passed #1388391
amd64 linux
system:gcc:tumbleweed:amd64

00:12:15

passed #1388392
amd64 linux
system:gcc:xenial:amd64

00:11:38

 
  Docs
passed #1388404
amd64 linux
docs

00:00:44

 
  Postcheck
passed #1388408
amd64 linux
cppcheck

00:00:54

passed #1388405
amd64 linux
flake8

00:00:20

passed #1388409
amd64 linux
gcov

00:00:32

77.0%
passed #1388406
amd64 linux
pylint

00:00:23

passed #1388407
amd64 linux
scan-build

00:04:16

 
Name Stage Failure
failed
system:gcc:focal:amd64 System
FAIL inline (exit status: 1)

$ test -n "${OUT_OF_TREE_WORKSPACE}" && mv "${OUT_OF_TREE_WORKSPACE}" "${CI_PROJECT_DIR}"
Uploading artifacts for failed job
Uploading artifacts...
untracked: found 1977 files

Uploading artifacts as "archive" to coordinator... ok
id=1388393 responseStatus=201 Created token=su1Cs1u2
Cleaning up file based variables
ERROR: Job failed: exit code 1
failed
system:clang:freebsd11:amd64 System
$ test -n "${OUT_OF_TREE_WORKSPACE}" && mv "${OUT_OF_TREE_WORKSPACE}" "${CI_PROJECT_DIR}"
Uploading artifacts for failed job
Uploading artifacts...
Runtime platform
arch=amd64 os=freebsd pid=65113 revision=ece86343 version=13.5.0
untracked: found 1509 files

Uploading artifacts as "archive" to coordinator... ok
id=1388402 responseStatus=201 Created token=QsQ6wUTy
Cleaning up file based variables
Unsupported run stage 'cleanup_file_variables'
ERROR: Job failed: exit status 1
failed
danger Precheck
 * [new branch]      main       -> origin/main



Failing the build, there are 3 fails.
Feedback: https://gitlab.isc.org/isc-projects/bind9/merge_requests/4528#note_185513

Cleaning up file based variables
ERROR: Job failed: exit code 1