gst: don't use volatile to mean atomic

volatile is not sufficient to provide atomic guarantees and real atomics
should be used instead.  GCC 11 has started warning about using volatile
with atomic operations.

https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1719

Discovered in gstreamer/gst-plugins-good#868

Part-of: <gstreamer/gst-editing-services!237>
29 jobs for !237 with backport-mr-234-into-1.18-gst-es-drop-volatile in 67 minutes and 57 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Build Docker
passed #8795670
alpine amd64 manifest builder docker

00:00:20

passed #8795669
android docker

00:00:26

passed #8795668
cerbero fedora amd64 docker

00:00:19

passed #8795667
fedora amd64 docker

00:00:22

passed #8795671
gst-indent amd64 docker

00:00:17

 
  Preparation
passed #8795673
gst indent

00:00:11

passed #8795672
manifest

00:00:30

 
  Build
passed #8795682
gstreamer
build cerbero cross-android universal

00:14:07

passed #8795686
gst-ios-14.3
build cerbero cross-ios universal

00:28:38

passed #8795683
gstreamer
build cerbero cross win32

00:08:40

passed #8795684
gstreamer
build cerbero cross win64

00:05:58

passed #8795681
gstreamer
build cerbero fedora x86_64

00:06:15

passed #8795685
gst-macos-11.1
build cerbero macos x86_64

00:15:25

passed #8795677
build clang fedora x86_64

00:09:16

manual #8795680
docker windows 1809 allowed to fail manual
build msys2
passed #8795674
build nodebug fedora x86_64

00:08:39

passed #8795675
build static fedora x86_64

00:08:50

passed #8795676
build static nodebug fedora x86_64

00:07:18

passed #8795678
docker windows 1809
build vs2017 amd64

00:12:45

passed #8795679
docker windows 1809
build vs2017 x86

00:12:24

 
  Test
passed #8795687
gstreamer
check fedora

00:06:30

passed #8795688
gstreamer
integration testsuites fedora 1/4

00:16:06

passed #8795689
gstreamer
integration testsuites fedora 2/4

00:13:42

passed #8795690
gstreamer
integration testsuites fedora 3/4

00:13:59

passed #8795691
gstreamer
integration testsuites fedora 4/4

00:15:55

passed #8795692
gstreamer
valgrind ges

00:05:51

 
  Integrate
passed #8795693
cross-android universal examples

00:07:59

passed #8795695
gst-ios-14.3
cross-ios universal examples

00:04:31

passed #8795694
documentation

00:15:49