Update the list of lexical decls in the TU for chained PCHs. This makes -ast-print show the decls from the dependent PCH.

llvm-svn: 109524
diff --git a/clang/lib/Frontend/PCHReader.cpp b/clang/lib/Frontend/PCHReader.cpp
index 37e1124..a0e3148 100644
--- a/clang/lib/Frontend/PCHReader.cpp
+++ b/clang/lib/Frontend/PCHReader.cpp
@@ -1539,6 +1539,16 @@
       F.LocalNumDecls = Record[0];
       break;
 
+    case pch::TU_UPDATE_LEXICAL: {
+      DeclContextInfo Info = {
+        /* No visible information */ 0, 0,
+        reinterpret_cast<const pch::DeclID *>(BlobStart),
+        BlobLen / sizeof(pch::DeclID)
+      };
+      DeclContextOffsets[Context->getTranslationUnitDecl()].push_back(Info);
+      break;
+    }
+
     case pch::LANGUAGE_OPTIONS:
       if (ParseLanguageOptions(Record) && !DisableValidation)
         return IgnorePCH;