clocksync: Add "send-gap" property to allow sending a new GAP event

This property will make clocksync element push a new GAP event
per incoming SEGEMENT event. By this property, we can make
downstream wake up or could be prerolled earlier even with very large
ts-offset value.
34 jobs for !598 with clocksync-gap in 1 minute and 39 seconds (queued for 5 seconds)
latest detached
Status Job ID Name Coverage
  Build Docker
passed #4142846
alpine amd64 manifest builder docker

00:00:37

passed #4142844
android docker

00:00:38

passed #4142843
cerbero fedora amd64 docker

00:00:52

passed #4142841
fedora amd64 docker

00:00:37

passed #4142848
gst-indent amd64 docker

00:00:45

 
  Preparation
passed #4142852
gst indent

00:00:28

manual #4142850
manual
manifest
 
  Build
created #4142873
gstreamer
build cerbero cross-android universal
created #4142882
gst-ios-13.2
build cerbero cross-ios universal
created #4142875
gstreamer
build cerbero cross win32
created #4142877
gstreamer
build cerbero cross win64
created #4142871
gstreamer
build cerbero fedora x86_64
created #4142879
gst-macos-10.15
build cerbero macos x86_64
created #4142860
build clang fedora x86_64
created #4142868
1809 windows docker allowed to fail manual
build msys2
created #4142854
build nodebug fedora x86_64
created #4142856
build static fedora x86_64
created #4142858
build static nodebug fedora x86_64
created #4142862
1809 windows docker
build vs2017 amd64
created #4142865
1809 windows docker
build vs2017 x86
 
  Test
created #4142884
gstreamer
check fedora
created #4142886
gstreamer
integration testsuites fedora 1/4
created #4142887
gstreamer
integration testsuites fedora 2/4
created #4142888
gstreamer
integration testsuites fedora 3/4
created #4142889
gstreamer
integration testsuites fedora 4/4
created #4142894
gstreamer
valgrind bad
created #4142891
gstreamer
valgrind base
created #4142890
gstreamer
valgrind core
created #4142895
gstreamer
valgrind ges
created #4142892
gstreamer
valgrind good
created #4142893
gstreamer
valgrind ugly
 
  Integrate
created #4142896
cross-android universal examples
created #4142898
gst-ios-13.2
cross-ios universal examples
created #4142897
documentation