exit(2) on unsupported positional arguments on command line

Change-Id: I32f9565c649a149638878a7283ddd8407ddff1ed
diff --git a/src/osysmon_main.c b/src/osysmon_main.c
index 07a065e..206246c 100644
--- a/src/osysmon_main.c
+++ b/src/osysmon_main.c
@@ -197,6 +197,11 @@
 			break;
 		}
 	}
+
+	if (argc > optind) {
+		fprintf(stderr, "Unsupported positional arguments on command line\n");
+		exit(2);
+	}
 }
 
 static struct osmo_timer_list print_timer;