test: add test case for issue 4365

This is an update of http://golang.org/cl/151410043 by Tim Shen.

Change-Id: I43ab7fcedd785059c535f45a3c8cdb7b618c1499
Reviewed-on: https://go-review.googlesource.com/4873Reviewed-by: David Crawshaw <crawshaw@golang.org>

test/fixedbugs/issue4365.go

+// errorcheck
+
+// Copyright 2015 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.
+
+// Test that fields hide promoted methods.
+// http://golang.org/issue/4365
+
+package main
+
+type T interface {
+        M()
+}
+
+type M struct{}
+
+func (M) M() {}
+
+type Foo struct {
+        M
+}
+
+func main() {
+        var v T = Foo{} // ERROR "has no methods|not a method|cannot use"
+        _ = v
+}