message: add system call sys_abort
diff: @@ -44,6 +44,11 @@ pub extern "C" fn sys_exit(arg: i32) -> ! {
  core_scheduler().exit(arg);
  }
  +#[no_mangle]
  +pub extern "C" fn sys_abort() -> ! {
  + sys_exit(-1);
  +}
  +
  #[no_mangle]
  pub extern "C" fn sys_sbrk(incr: isize) -> usize {
  // Get the boundaries of the task heap and verify that they are suitable for sbrk.
  