launch_daemon: Added ability to enable/disable a job.

* Instead of just starting/stopping it.
* Also available via the launch_roster command.

headers/private/app/LaunchDaemonDefs.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015, Haiku, Inc. All Rights Reserved.
+ * Copyright 2015-2016, Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -27,6 +27,7 @@ enum {
 	B_GET_LAUNCH_DATA			= 'lnda',
 	B_LAUNCH_TARGET				= 'lntg',
 	B_LAUNCH_JOB				= 'lnjo',
+	B_ENABLE_LAUNCH_JOB			= 'lnje',
 	B_STOP_LAUNCH_JOB			= 'lnsj',
 	B_LAUNCH_SESSION			= 'lnse',
 	B_REGISTER_SESSION_DAEMON	= 'lnrs',

headers/private/app/LaunchRoster.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Haiku, Inc. All rights reserved.
+ * Copyright 2015-2016 Haiku, Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _LAUNCH_ROSTER_H
@@ -36,6 +36,7 @@ public:
 
 			status_t			Start(const char* name);
 			status_t			Stop(const char* name, bool force = false);
+			status_t			SetEnabled(const char* name, bool enabled);
 
 			status_t			StartSession(const char* login);