make libwayland-dev multiarch aware

This patch that makes libwayland-dev Multi-Arch:same. This is done by
splitting that package into -dev and -bin. The -bin package contains
the wayland-scanner executable, and it is Multi-Arch:foreign.

Based on a patch from Dima Kogan

Closes: #739400

Signed-off-by: Héctor Orón Martínez <zumbi@debian.org>