compositor-drm: Reject heads if HDR head exists

Don't attach a head to an output which has a head with HDR capabilities.

Signed-off-by: Harish Krupo <harish.krupo.kps@intel.com>
2 jobs for hdr in 1 minute and 52 seconds (queued for 17 seconds)
Status Job ID Name Coverage
  Container Prep
passed #257089
container_prep

00:00:30

 
  Build
failed #257090
build-native-meson

00:01:22

 
Name Stage Failure
failed
build-native-meson Build

clients/meson.build:363:2: ERROR: Dependency "libavutil" not found, tried pkgconfig

A full log can be found at /builds/harishkrupo/weston/build-weston-f7d029fe05c4041c8a5bbb7006634c84d2724b17-257090/meson-logs/meson-log.txt
Uploading artifacts...
build-*/meson-logs: found 2 matching files
prefix-*: found 54 matching files
Uploading artifacts to coordinator... ok id=257090 responseStatus=201 Created token=NZHXrVuY
ERROR: Job failed: exit code 1