add deadlock mutex package

write to deadlock stderr after closing gocui

more deadlock checking

vendor/github.com/petermattis/goid/runtime_go1.6.go

@@ -0,0 +1,42 @@
+// +build gc,go1.6,!go1.9
+
+package goid
+
+// Just enough of the structs from runtime/runtime2.go to get the offset to goid.
+// See https://github.com/golang/go/blob/release-branch.go1.6/src/runtime/runtime2.go
+
+type stack struct {
+	lo uintptr
+	hi uintptr
+}
+
+type gobuf struct {
+	sp   uintptr
+	pc   uintptr
+	g    uintptr
+	ctxt uintptr
+	ret  uintptr
+	lr   uintptr
+	bp   uintptr
+}
+
+type g struct {
+	stack       stack
+	stackguard0 uintptr
+	stackguard1 uintptr
+
+	_panic       uintptr
+	_defer       uintptr
+	m            uintptr
+	stackAlloc   uintptr
+	sched        gobuf
+	syscallsp    uintptr
+	syscallpc    uintptr
+	stkbar       []uintptr
+	stkbarPos    uintptr
+	stktopsp     uintptr
+	param        uintptr
+	atomicstatus uint32
+	stackLock    uint32
+	goid         int64 // Here it is!
+}