v4l2object: handle GST_VIDEO_TRANSFER_BT601

V4L2 makes no difference between the BT.601 and BT.709 transfer
functions [1], but GStreamer does since 1.18 [2].

Adapt gst_v4l2_object_get_colorspace() and
gst_v4l2_object_set_format_full().

[1] https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/colorspaces-details.html#colorspace-smpte-170m-v4l2-colorspace-smpte170m
[2] gstreamer/gst-plugins-base!724

Part-of: <gstreamer/gst-plugins-good!900>
32 jobs for !900 with backport-mr-856-into-1.18-v4l2-bt601 in 32 minutes and 12 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Build Docker
passed #7955388
alpine amd64 manifest builder docker

00:00:27

passed #7955387
android docker

00:00:40

passed #7955386
cerbero fedora amd64 docker

00:00:40

passed #7955385
fedora amd64 docker

00:00:41

passed #7955389
gst-indent amd64 docker

00:00:26

 
  Preparation
passed #7955391
gst indent

00:00:32

passed #7955390
manifest

00:00:16

 
  Build
passed #7955400
gstreamer
build cerbero cross-android universal

00:06:55

passed #7955404
gst-ios-14.3
build cerbero cross-ios universal

00:21:11

passed #7955401
gstreamer
build cerbero cross win32

00:04:26

passed #7955402
gstreamer
build cerbero cross win64

00:04:51

passed #7955399
gstreamer
build cerbero fedora x86_64

00:05:08

passed #7955403
gst-macos-11.1
build cerbero macos x86_64

00:12:46

passed #7955395
build clang fedora x86_64

00:06:22

manual #7955398
docker windows 1809 allowed to fail manual
build msys2
passed #7955392
build nodebug fedora x86_64

00:05:57

passed #7955393
build static fedora x86_64

00:05:09

passed #7955394
build static nodebug fedora x86_64

00:03:32

passed #7955396
docker windows 1809
build vs2017 amd64

00:08:26

passed #7955397
docker windows 1809
build vs2017 x86

00:08:37

 
  Test
passed #7955405
gstreamer
check fedora

00:04:40

passed #7955406
gstreamer
integration testsuites fedora 1/4

00:13:07

passed #7955407
gstreamer
integration testsuites fedora 2/4

00:13:42

passed #7955408
gstreamer
integration testsuites fedora 3/4

00:13:26

passed #7955409
gstreamer
integration testsuites fedora 4/4

00:13:42

passed #7958082
gstreamer
valgrind bad

00:06:04

passed #7955412
gstreamer
valgrind ges

00:05:58

passed #7955410
gstreamer
valgrind good

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failed #7955411
gstreamer
valgrind bad

00:05:36

 
  Integrate
passed #7955413
cross-android universal examples

00:07:29

passed #7955415
gst-ios-14.3
cross-ios universal examples

00:03:56

passed #7955414
documentation

00:10:31