cgo: add missing semicolon in generated struct

This affected certain signatures needing padding
like:

//export Foo
func Foo() (int, C.long) { ... }

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4745047

misc/cgo/test/Makefile

@@ -11,6 +11,7 @@ CGOFILES=\
 	basic.go\
 	callback.go\
 	env.go\
+	exports.go\
 	issue1222.go\
 	issue1328.go\
 	issue1560.go\

misc/cgo/test/exports.go

+// Copyright 2011 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 cgotest
+
+import "C"
+
+//export ReturnIntLong
+func ReturnIntLong() (int, C.long) {
+	return 1, 2
+}

src/cmd/cgo/out.go

@@ -412,7 +412,7 @@ func (p *Package) writeExports(fgo2, fc, fm *os.File) {
 				t := p.cgoType(atype)
 				if off%t.Align != 0 {
 					pad := t.Align - off%t.Align
-					ctype += fmt.Sprintf("\t\tchar __pad%d[%d]\n", npad, pad)
+					ctype += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
 					off += pad
 					npad++
 				}