glib: Support for java/android
Letting glib have access to the application context is practically a necessity for my ongoing work of GTK to android (gtk!7555).
The current implementation is a base, further necessary additions (most importantly a content:// file resolver and Gio wrappers for Java I/O-Streams, but probably something else I just haven't thought of yet too.)
This will require some sort of coordination with GStreamer, as they've worked on glib android integration already, which is mostly incompatible with this / my implementation in GTK. @xclaesse