fix eventlet worker boot

new version of eventlet uses an external process to check a feature at
runtime (monotonic). ut since gunicorn already installed a signal handler,
eventlet never get the return and then was raising a runtime error making the worker crash.

This patch fix it by patching the worker after it has been initialized
and the signals resetted.

fix #1584

gunicorn/workers/geventlet.py

@@ -99,8 +99,8 @@ class EventletWorker(AsyncWorker):
             return super(EventletWorker, self).is_already_handled(respiter)
 
     def init_process(self):
-        self.patch()
         super(EventletWorker, self).init_process()
+        self.patch()
 
     def handle_quit(self, sig, frame):
         eventlet.spawn(super(EventletWorker, self).handle_quit, sig, frame)