Don't allow non-const pointers to Type instances

This makes the namespace into a read only datastructure of types
with a few methods to load types during parsing.

Bug: 24303749
Test: compiles, unittests

Change-Id: I0873e520d771b348a1a8ec9515b6e7b9a8a29298
diff --git a/generate_java.cpp b/generate_java.cpp
index 98f93bc..09a4410 100644
--- a/generate_java.cpp
+++ b/generate_java.cpp
@@ -18,7 +18,7 @@
 }
 
 Variable*
-VariableFactory::Get(Type* type)
+VariableFactory::Get(const Type* type)
 {
     char name[100];
     sprintf(name, "%s%d", m_base.c_str(), m_index);