kernel/debug: Report killing signals

Adds a `signal` field to the `team_deleted` event. Since killing
signals like `SIGKILL` and `SIGKILLTHR` do not generate a
`signal_received` event, debuggers would only see a `team_deleted`
message with the `status` field set to 0. This makes debuggers like
GDB think that the debuggee has exited with a status code of 0.

To correctly report these signals, when a killing signal is sent
to a team, this signal is relayed to the main thread instead of
defaulting to just a `SIGKILLTHR` for both cases.

Change-Id: If69c9e2e4d87bfbd31f654f5cb6f696ac69ef777
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7756
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

headers/os/kernel/debugger.h

@@ -561,6 +561,7 @@ typedef struct {
 	debug_origin	origin;			// thread is < 0, team is the deleted team
 									// (asynchronous message)
 	status_t		status;			// the exit code of the team
+	int				signal;			// the signal causing the exit, < 0 if none
 	team_usage_info	usage;			// the usage info of the team
 } debug_team_deleted;
 

headers/private/kernel/user_debugger.h

@@ -259,7 +259,7 @@ bool user_debug_handle_signal(int signal, struct sigaction *handler,
 void user_debug_stop_thread();
 void user_debug_team_created(team_id teamID);
 void user_debug_team_deleted(team_id teamID, port_id debuggerPort, status_t status,
-		team_usage_info* usageInfo);
+		int signal, team_usage_info* usageInfo);
 void user_debug_team_exec();
 void user_debug_update_new_thread_flags(Thread* thread);
 void user_debug_thread_created(thread_id threadID);