lib: Include OstreeRemote and OstreeCollectionRef in GIR

Now that g-ir-scanner is being told about ENABLE_EXPERIMENTAL_API, it
can include these types correctly. Drop the __GI_SCANNER__ guards in the
header files so that all the declarations are found.

After this, you can actually construct the types normally:

>>> OSTree.CollectionRef.new('com.example.Foo', 'bar')
<OSTree.CollectionRef object at 0x7f2bba4c7528 (OstreeCollectionRef at 0x55c033ff2f30)>

Closes: #1337
Approved by: pwithnall

src/libostree/ostree-remote.h

@@ -47,14 +47,12 @@ G_BEGIN_DECLS
 typedef struct OstreeRemote OstreeRemote;
 #endif
 
-#ifndef __GI_SCANNER__
 _OSTREE_PUBLIC
 GType ostree_remote_get_type (void) G_GNUC_CONST;
 _OSTREE_PUBLIC
 OstreeRemote *ostree_remote_ref (OstreeRemote *remote);
 _OSTREE_PUBLIC
 void ostree_remote_unref (OstreeRemote *remote);
-#endif /* GI_SCANNER */
 
 _OSTREE_PUBLIC
 const gchar *ostree_remote_get_name (OstreeRemote *remote);