libmalcontent-ui: Port to libappstream
Depend on libappstream-dev, and include appstream.h instead of appstream-glib.h.
We can depend on a new enough version of libappstream that all the
content rating symbols we need are available, which means that
gs-content-rating.[ch]
can be dropped entirely.
Turns out no code changes are needed other than that.
Closes #51 (closed)
Edited by Philip Withnall