add deadlock mutex package

write to deadlock stderr after closing gocui

more deadlock checking

vendor/github.com/petermattis/goid/goid_gccgo.go

@@ -0,0 +1,25 @@
+// Copyright 2018 Peter Mattis.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// permissions and limitations under the License. See the AUTHORS file
+// for names of contributors.
+
+// +build gccgo
+
+package goid
+
+//extern runtime.getg
+func getg() *g
+
+func Get() int64 {
+	return getg().goid
+}