exitkills doesn't pass the error code

[spion-h4]

It would be useful if the error code of the process is passed as the error code of chaperone if exitkills is enabled for a process.

chaperone/chaperone/cproc/subproc.py

Lines 560 to 572 in 9ff2c3a

	def process_exit(self, code):
	self.returncode = code
	if self._exit_event:
	self._exit_event.set()
	self._exit_event = None
	if self.exit_kills:
	self.logwarn("{0} terminated with exit_kills enabled", self.service.name);
	# Since we're dead, and the system is going away, disable any process management
	self._proc = None
	self.pid = None
	self._kill_system();

[spion-h4]

Patching _kill_system to pass the returncode would probably work:

def _kill_system(self):
    self.family.controller.kill_system(self.returncode)