Add a TypeSystem for Go

Add GoASTContext and DWARFASTParserGo to support go.

Differential Revision: http://reviews.llvm.org/D12585

llvm-svn: 247629
diff --git a/lldb/source/Symbol/SymbolFile.cpp b/lldb/source/Symbol/SymbolFile.cpp
index 0923578..e8e5f49 100644
--- a/lldb/source/Symbol/SymbolFile.cpp
+++ b/lldb/source/Symbol/SymbolFile.cpp
@@ -93,7 +93,10 @@
 TypeSystem *
 SymbolFile::GetTypeSystemForLanguage (lldb::LanguageType language)
 {
-    return m_obj_file->GetModule()->GetTypeSystemForLanguage (language);
+    TypeSystem *type_system = m_obj_file->GetModule()->GetTypeSystemForLanguage(language);
+    if (type_system)
+        type_system->SetSymbolFile(this);
+    return type_system;
 }
 
 uint32_t