Fix the tag 'size' when viewing a profile in cd-iccdump with newer lcms versions

Newer versions of lcms2 don't have the bug where they read the whole tag out,
and now returns the size of the read (a good thing!).
Only include libudev in Requires.private on Linux

Resolves: https://bugs.freedesktop.org/show_bug.cgi?id=72539
libcolord: Do not use G_GNUC_WARN_UNUSED_RESULT when uninhibiting

Clients don't need to know this has failed if a device was never inhibited in
the first place.
libcolorhug: Handle failure to initialise GUsb in self-tests

This can fail, and does in my VMs and on the Ubuntu autopkgtest infrastructure.
Since there are other tests of libcolorhug that can usefully be run, handle this
like a failure to find a ColorHug on the USB bus, which is already non-fatal.
Use the corect sensor-kind values for GretagMacbeth sensors

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1000910