cmd/utils, internal/debug: show all stacks for 10x Ctrl-C induced panic

Go 1.6 only prints stacks for the current goroutine by default,
but for this panic we want to see all of them.

internal/debug/loudpanic_fallback.go

@@ -0,0 +1,24 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// +build !go1.6
+
+package debug
+
+// LoudPanic panics in a way that gets all goroutine stacks printed on stderr.
+func LoudPanic(x interface{}) {
+	panic(x)
+}