On watchdog expiry, raise SIGABRT instead of asserting 0, so it can be caught in gdb, also reset it to avoid keeping shouting

src/core/task.c

@@ -1039,11 +1039,13 @@ static void *watchdog_func(void *foo STARPU_ATTRIBUTE_UNUSED)
 			if (getenv("STARPU_WATCHDOG_CRASH"))
 			{
 				fprintf(stderr,"Crashing the process\n");
-				assert(0);
+				raise(SIGABRT);
 			}
 			else
 				fprintf(stderr,"Set the STARPU_WATCHDOG_CRASH environment variable if you want to abort the process in such a case\n");
 		}
+		/* Only shout again after another period */
+		config->watchdog_ok = 1;
 	}
 	STARPU_PTHREAD_MUTEX_UNLOCK(&config->submitted_mutex);
 	return NULL;