Drop busname unit type

Since busname units are only useful with kdbus, they weren't actively
used. This was dead code, only compile-tested. If busname units are
ever added back, it'll be cleaner to start from scratch (possibly reverting
parts of this patch).

src/basic/unit-name.h

@@ -28,7 +28,6 @@
 typedef enum UnitType {
         UNIT_SERVICE = 0,
         UNIT_SOCKET,
-        UNIT_BUSNAME,
         UNIT_TARGET,
         UNIT_DEVICE,
         UNIT_MOUNT,
@@ -73,19 +72,6 @@ typedef enum AutomountState {
         _AUTOMOUNT_STATE_INVALID = -1
 } AutomountState;
 
-typedef enum BusNameState {
-        BUSNAME_DEAD,
-        BUSNAME_MAKING,
-        BUSNAME_REGISTERED,
-        BUSNAME_LISTENING,
-        BUSNAME_RUNNING,
-        BUSNAME_SIGTERM,
-        BUSNAME_SIGKILL,
-        BUSNAME_FAILED,
-        _BUSNAME_STATE_MAX,
-        _BUSNAME_STATE_INVALID = -1
-} BusNameState;
-
 /* We simply watch devices, we cannot plug/unplug them. That
  * simplifies the state engine greatly */
 typedef enum DeviceState {
@@ -339,9 +325,6 @@ UnitActiveState unit_active_state_from_string(const char *s) _pure_;
 const char* automount_state_to_string(AutomountState i) _const_;
 AutomountState automount_state_from_string(const char *s) _pure_;
 
-const char* busname_state_to_string(BusNameState i) _const_;
-BusNameState busname_state_from_string(const char *s) _pure_;
-
 const char* device_state_to_string(DeviceState i) _const_;
 DeviceState device_state_from_string(const char *s) _pure_;