systemctl: introduce -r switch to show units running in local containers in addition to the host

src/libsystemd/sd-bus/bus-util.c

@@ -1192,6 +1192,8 @@ int bus_parse_unit_info(sd_bus_message *message, UnitInfo *u) {
         assert(message);
         assert(u);
 
+        u->machine = NULL;
+
         return sd_bus_message_read(
                         message,
                         "(ssssssouso)",

src/libsystemd/sd-bus/bus-util.h

@@ -123,6 +123,7 @@ int bus_log_parse_error(int r);
 int bus_log_create_error(int r);
 
 typedef struct UnitInfo {
+        const char *machine;
         const char *id;
         const char *description;
         const char *load_state;