core/trivial: rename "source" field of addresses and routes

The "source" field of NMPlatformIPRoute (now "rt_source") maps to the
protocol field of the route. The source of NMPlatformIPAddress (now
"addr_source") has no direct equivalent in the kernel.

As their use is different, they should have different names. Also,
the name "source" is used all over the place. Hence give the fields
a more distinct name.

src/platform/nmp-object.c

@@ -920,7 +920,7 @@ _vt_cmd_obj_is_alive_ipx_route (const NMPObject *obj)
 	 * Instead we create a dead object, and nmp_cache_update_netlink()
 	 * will remove the old version of the update.
 	 **/
-	return obj->object.ifindex > 0 && (obj->ip_route.source != _NM_IP_CONFIG_SOURCE_RTM_F_CLONED);
+	return obj->object.ifindex > 0 && (obj->ip_route.rt_source != _NM_IP_CONFIG_SOURCE_RTM_F_CLONED);
 }
 
 gboolean