Do not worry over non-existant debug socket

If the socket was not created, do not error on exit because it isn't there to be cleaned up.

confluent_server/confluent/main.py

@@ -134,7 +134,10 @@ def dumptrace(signalname, frame):
 def doexit():
     if not havefcntl:
         return
-    os.remove('/var/run/confluent/dbg.sock')
+    try:
+        os.remove('/var/run/confluent/dbg.sock')
+    except OSError:
+        pass
     pidfile = open('/var/run/confluent/pid')
     pid = pidfile.read()
     if pid == str(os.getpid()):