Add multiarch metadata to libxkbcommon*dev packages

[Derek Gasaway]

Release: Artful Aardvark 17.10
Package Version: 0.7.1-2

As far as I can tell (after creating a local patch and building and installing them as Multi-Arch: same) libxkbcommon-dev and libxkbcommon-x11-dev can be safely marked as Multi-Arch: same with no additional changes. Note that in order to cross-build the package, I also patched the build dependency x11-xkb-utils as Multi-Arch: allowed, and then used an :any dep. The use of :any as a dep is possibly appropriate, as I successfully built the package this way, I think only the tests depend on it, and they seem to call the binaries at runtime rather than compiling against them.

Also, tests/x11comp is actually deactivated (since Mar 13, 2016 upstream), and seems to be the only place that uses one of the x11-xkb-utils binaries, so maybe this dependency can just be removed?