misc/cgo/test: add -ldl to LDFLAGS on Linux, ignore issue4029 on windows (fix build)

R=golang-dev
CC=golang-dev
https://golang.org/cl/6631054

misc/cgo/test/issue4029.go

@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !windows
+
 package cgotest
 
 /*
 #include <dlfcn.h> 
+#cgo linux LDFLAGS: -ldl
 */
 import "C"
 

misc/cgo/test/issue4029w.go

+// Copyright 2012 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.
+
+// +build windows
+
+package cgotest
+
+import "testing"
+
+func test4029(t *testing.T) {
+}