- filed bug: label identifiers should not be allowed to match

other identifiers in the same scope.

R=r
OCL=13431
CL=13431

test/bugs/bug077.go

+// $G $D/$F.go || echo BUG: should compile
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func main() {
+	var exit int;
+exit:  // this shouldn't be legal
+}
+
+/*
+Within a scope, an identifier should have only one association - it cannot be
+a variable and a label at the same time.
+*/