scanner: add defines for wayland interface versions

Currently, it is cumbersome for clients that want to know what version of an interface is supported at compile time. This can especially matter in cases where the compositor and client aren't neccesarily compiled against the same wayland and wayland protocol versions. Provide more information by adding a simple int define for all interfaces that give the version that is already defined in the source xml file.

Would it make sense to put this in the enum-header too?