Don't call virtual methods in TypeNamespace constructors

While probably safe in this particular context because of this specific
class structure, it is bad practice to call virtual methods in constructors.

Bug: None
Test: unittests continue to pass

Change-Id: I3c9a435efd89a2c2bd7ce576aed585b8ab766bda
diff --git a/type_java.cpp b/type_java.cpp
index e922f9f..ff05440 100644
--- a/type_java.cpp
+++ b/type_java.cpp
@@ -705,7 +705,7 @@
 
 // ================================================================
 
-JavaTypeNamespace::JavaTypeNamespace() {
+void JavaTypeNamespace::Init() {
   Add(new BasicType(this, "void", "XXX", "XXX", "XXX", "XXX", "XXX"));
 
   m_bool_type = new BooleanType(this);