clock: define AUTO_CLEANUP_FREE_FUNC for GstClockID

GstClockID is secretly a gpointer so we can't use g_autoptr(),
instead user can do:
  g_auto (GstClockID) clock_id = 0;

Part-of: <gstreamer/gstreamer!770>
35 jobs for !770 with backport-mr-769-into-1.18-auto-clock-id in 32 minutes and 45 seconds (queued for 5 seconds)
detached
Status Job ID Name Coverage
  Build Docker
passed #7914873
alpine amd64 manifest builder docker

00:00:56

passed #7914872
android docker

00:00:34

passed #7914871
cerbero fedora amd64 docker

00:00:56

passed #7914870
fedora amd64 docker

00:00:56

passed #7914874
gst-indent amd64 docker

00:00:34

 
  Preparation
passed #7914876
gst indent

00:00:20

passed #7914875
manifest

00:00:36

 
  Build
passed #7914885
gstreamer
build cerbero cross-android universal

00:12:38

passed #7914889
gst-ios-14.3
build cerbero cross-ios universal

00:21:28

passed #7914886
gstreamer
build cerbero cross win32

00:09:37

passed #7914887
gstreamer
build cerbero cross win64

00:06:51

passed #7914884
gstreamer
build cerbero fedora x86_64

00:06:01

passed #7914888
gst-macos-11.1
build cerbero macos x86_64

00:13:48

passed #7914880
build clang fedora x86_64

00:08:02

manual #7914883
docker windows 1809 allowed to fail manual
build msys2
passed #7914877
build nodebug fedora x86_64

00:05:31

passed #7914878
build static fedora x86_64

00:07:27

passed #7914879
build static nodebug fedora x86_64

00:07:22

passed #7914881
docker windows 1809
build vs2017 amd64

00:09:45

passed #7914882
docker windows 1809
build vs2017 x86

00:09:56

 
  Test
passed #7916465
gstreamer
check fedora

00:05:11

passed #7914891
gstreamer
integration testsuites fedora 1/4

00:16:23

passed #7914892
gstreamer
integration testsuites fedora 2/4

00:16:10

passed #7914893
gstreamer
integration testsuites fedora 3/4

00:14:24

passed #7914894
gstreamer
integration testsuites fedora 4/4

00:19:39

passed #7914899
gstreamer
valgrind bad

00:05:59

passed #7914896
gstreamer
valgrind base

00:09:22

passed #7914895
gstreamer
valgrind core

00:08:31

passed #7914900
gstreamer
valgrind ges

00:08:34

passed #7914897
gstreamer
valgrind good

00:12:01

passed #7914898
gstreamer
valgrind ugly

00:05:16

failed #7914890
gstreamer
check fedora

00:13:00

 
  Integrate
passed #7914901
cross-android universal examples

00:07:58

passed #7914903
gst-ios-14.3
cross-ios universal examples

00:04:31

passed #7914902
documentation

00:10:24