bind: support reference types as struct fields.

Reference types here mean pointers to struct types and
exported interface types. Previously, gobind generated invalid
go/java sources.

Change-Id: Icd666ebbb8edb70c613311798d602fd88cb4479c
Reviewed-on: https://go-review.googlesource.com/9997
Reviewed-by: Alan Donovan <adonovan@google.com>

bind/java/SeqTest.java

@@ -246,8 +246,15 @@ public class SeqTest extends AndroidTestCase {
 
   public void testUnnamedParams() {
     final String msg = "1234567";
-    assertEquals("Want the length of \"1234567\" passed after unnamed params",
+    assertEquals("want the length of \"1234567\" passed after unnamed params",
 		    7, Testpkg.UnnamedParams(10, 20, msg));
   }
 
+  public void testPointerToStructAsField() {
+    Testpkg.Node a = Testpkg.NewNode("A");
+    Testpkg.Node b = Testpkg.NewNode("B");
+    a.setNext(b);
+    String got = a.String();
+    assertEquals("want Node A points to Node B", "A:B:<end>", got);
+  }
 }

bind/java/testpkg/testpkg.go

@@ -124,3 +124,19 @@ func AppendToString(str string, someBytes []byte) []byte {
 func UnnamedParams(_, _ int, p0 string) int {
 	return len(p0)
 }
+
+type Node struct {
+	V    string
+	Next *Node
+}
+
+func NewNode(name string) *Node {
+	return &Node{V: name}
+}
+
+func (a *Node) String() string {
+	if a == nil {
+		return "<end>"
+	}
+	return a.V + ":" + a.Next.String()
+}