videoconvert: Preserve and forward upstream colorimetry

When upstream provides colorimetry explicitly, preserve it as mush as
possible and set the converted colorimetry to output caps.

Closes gstreamer/gst-plugins-base#614
17 jobs for forward-colorimetry in 75 minutes and 10 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #317558
gst indent

00:00:34

passed #317557
manifest

00:00:54

 
  Build
passed #317559
build fedora x86_64

00:06:36

passed #317560
build nodebug fedora x86_64

00:06:33

 
  Test
passed #317561
check fedora

00:04:02

passed #317562
integration testsuites fedora

00:26:59

 
  Full Builds
passed #317564
build cerbero android universal

00:11:17

passed #317565
build cerbero cross win32

00:06:57

passed #317566
build cerbero cross win64

00:04:34

passed #317563
build cerbero fedora x86_64

00:05:16

 
  Full Tests
passed #317570
valgrind bad

00:16:38

passed #317567
valgrind base

00:18:56

passed #317571
valgrind ges

00:10:26

passed #317568
valgrind good

00:19:58

passed #317569
valgrind ugly

00:02:03

 
  Apps
passed #317572
android universal examples

00:05:48

 
  Deploy
passed #317573
documentation

00:03:33