glib 2.36 and friends

This needs to be tested with a good sampling of `brew uses glib`.

Already I've had issues building gtk+, in which the build hands running `gtk-update-icon-cache`:

```
./gtk-update-icon-cache --force --ignore-theme-index		\
	   --source builtin_icons stock-icons > gtkbuiltincache.h.tmp &&        \
	mv gtkbuiltincache.h.tmp gtkbuiltincache.h
```

It would be useful to know if anyone can reproduce that.