We cannot rely on any build order, except the one we specify ourselves.
St depends on various generated files; other targets depend on those
files existing, so they can be included. There is no direct relationship
between targets and files, unless we declare a dependency, using the
Meson declare_dependency() constructor — which allows us to replace the
various `link_with` directives with the more appropriate `dependencies`
one, and also allows us to specify sources that must exist by the time
we build those targets.
Meson is on track to replace autotools as the build system of choice,
so support it in addition to autotools. If all goes well, we'll
eventually be able to drop the latter ...
https://bugzilla.gnome.org/show_bug.cgi?id=783229
