Meson: Fix declare_dependency() calls

Turns out the fix in commit 93555577c wasn't enough, when using glib as
subproject and the parent project uses only libgio_dep, and include
<gi18n.h>, it won't find libintl.h because it's in the
include_directories of libglib_dep. Fix that by declaring dependencies
explicitly, which is the right thing to do since glib and gobject are
public dependencies of gio. That reflects what we do for the pkg-config
file as well.

gobject/meson.build

@@ -84,7 +84,8 @@ pkg.generate(libraries : libgobject,
 )
 
 libgobject_dep = declare_dependency(link_with : libgobject,
-  include_directories : [configinc, glibinc, gobjectinc])
+  include_directories : [gobjectinc],
+  dependencies : [libglib_dep])
 
 python_tools = [
   'glib-genmarshal',