HAL_PX4: format panic messages with a newline

libraries/AP_HAL_PX4/Scheduler.cpp

@@ -190,6 +190,7 @@ void *PX4Scheduler::_timer_thread(void)
 void PX4Scheduler::panic(const prog_char_t *errormsg) 
 {
     write(1, errormsg, strlen(errormsg));
+    write(1, "\n", 1);
     hal.scheduler->delay_microseconds(10000);
     _px4_thread_should_exit = true;
     exit(1);