Add Alpine Linux to GitLab CI

Ensure BIND is continuously tested on Alpine Linux as it is commonly
used as a base for Docker containers and employs a less popular libc
implementation, musl libc.

(cherry picked from commit 326a334b)
55 jobs for !2210 with 1171-alpine-linux-tweaks-v9_11 in 20 minutes and 35 seconds (queued for 6 seconds)
detached
Status Job ID Name Coverage
  Precheck
passed #289867
amd64 linux
🐞:sid:amd64

00:01:11

passed #289866
amd64 linux
misc:sid:amd64

00:00:22

 
  Build
passed #289880
amd64 linux
asan:sid:amd64

00:04:57

passed #289881
amd64 linux
clang:stretch:amd64

00:03:47

passed #289882
i386 linux
clang:stretch:i386

00:01:49

passed #289868
amd64 linux
docs:sid:amd64

00:00:56

passed #289943
amd64 linux
gcc:alpine3.10:amd64

00:02:14

passed #289879
amd64 linux
gcc:bionic:amd64

00:02:48

passed #289874
i386 linux
gcc:buster:amd64

00:02:00

passed #289870
amd64 linux
gcc:centos6:amd64

00:01:59

passed #289871
amd64 linux
gcc:centos7:amd64

00:02:34

passed #289877
amd64 linux
gcc:fedora29:amd64

00:02:20

passed #289872
amd64 linux
gcc:jessie:amd64

00:01:47

passed #289875
amd64 linux
gcc:sid:amd64

00:01:46

passed #289876
i386 linux
gcc:sid:i386

00:02:14

passed #289873
amd64 linux
gcc:stretch:amd64

00:02:20

passed #289878
amd64 linux
gcc:xenial:amd64

00:01:58

passed #289885
amd64 linux
noassert:sid:amd64

00:02:08

passed #289883
amd64 linux
nocrypto:sid:amd64

00:01:29

passed #289884
amd64 linux
pkcs11:sid:amd64

00:02:34

passed #289869
amd64 linux
gcc:alpine3.10:amd64

00:03:27

 
  Test
passed #289908
amd64 linux
system:asan:sid:amd64

00:06:50

passed #289945
amd64 linux
system:gcc:alpine3.10:amd64

00:05:16

passed #289906
amd64 linux
system:gcc:bionic:amd64

00:06:05

passed #289896
i386 linux
system:gcc:buster:amd64

00:05:17

passed #289888
amd64 linux
system:gcc:centos6:amd64

00:05:28

passed #289890
amd64 linux
system:gcc:centos7:amd64

00:05:56

passed #289902
amd64 linux
system:gcc:fedora29:amd64

00:05:44

passed #289892
amd64 linux
system:gcc:jessie:amd64

00:05:52

passed #289898
amd64 linux
system:gcc:sid:amd64

00:05:52

passed #289900
i386 linux
system:gcc:sid:i386

00:05:42

passed #289894
amd64 linux
system:gcc:stretch:amd64

00:05:19

passed #289904
amd64 linux
system:gcc:xenial:amd64

00:05:45

passed #289915
amd64 linux
system:noassert:sid:amd64

00:05:30

passed #289911
amd64 linux
system:nocrypto:sid:amd64

00:03:33

passed #289913
amd64 linux
system:pkcs11:sid:amd64

00:05:28

passed #289909
amd64 linux
unit:asan:sid:amd64

00:01:59

passed #289910
amd64 linux
unit:clang:stretch:amd64

00:00:53

passed #289887
amd64 linux
unit:gcc:alpine3.10:amd64

00:01:07

passed #289907
amd64 linux
unit:gcc:bionic:amd64

00:01:12

passed #289897
i386 linux
unit:gcc:buster:amd64

00:01:05

passed #289889
amd64 linux
unit:gcc:centos6:amd64

00:01:07

passed #289891
amd64 linux
unit:gcc:centos7:amd64

00:01:07

passed #289903
amd64 linux
unit:gcc:fedora29:amd64

00:01:11

passed #289893
amd64 linux
unit:gcc:jessie:amd64

00:00:32

passed #289899
amd64 linux
unit:gcc:sid:amd64

00:00:57

passed #289901
i386 linux
unit:gcc:sid:i386

00:00:53

passed #289895
amd64 linux
unit:gcc:stretch:amd64

00:00:57

passed #289905
amd64 linux
unit:gcc:xenial:amd64

00:01:09

passed #289916
amd64 linux
unit:noassert:sid:amd64

00:01:10

passed #289912
amd64 linux
unit:nocrypto:sid:amd64

00:01:08

passed #289914
amd64 linux
unit:pkcs11:sid:amd64

00:01:06

canceled #289941
amd64 linux
system:gcc:alpine3.10:amd64

00:02:19

canceled #289939
amd64 linux
system:gcc:alpine3.10:amd64

00:01:51

failed #289886
amd64 linux
system:gcc:alpine3.10:amd64

00:05:54