[PCH] Overhaul how preprocessed entities are [de]serialized.

-Use an array of offsets for all preprocessed entities
-Get rid of the separate array of offsets for just macro definitions;
 for references to macro definitions use an index inside the preprocessed
 entities array.
-Deserialize each preprocessed entity lazily, at first request; not in bulk.

Paves the way for binary searching of preprocessed entities that will offer
efficiency and will simplify things on the libclang side a lot.

llvm-svn: 139809
diff --git a/clang/lib/Frontend/MultiplexConsumer.cpp b/clang/lib/Frontend/MultiplexConsumer.cpp
index 5aa65d7..8e746f6 100644
--- a/clang/lib/Frontend/MultiplexConsumer.cpp
+++ b/clang/lib/Frontend/MultiplexConsumer.cpp
@@ -37,7 +37,7 @@
   virtual void TypeRead(serialization::TypeIdx Idx, QualType T);
   virtual void DeclRead(serialization::DeclID ID, const Decl *D);
   virtual void SelectorRead(serialization::SelectorID iD, Selector Sel);
-  virtual void MacroDefinitionRead(serialization::MacroID, 
+  virtual void MacroDefinitionRead(serialization::PreprocessedEntityID, 
                                    MacroDefinition *MD);
 private:
   std::vector<ASTDeserializationListener*> Listeners;
@@ -79,7 +79,7 @@
 }
 
 void MultiplexASTDeserializationListener::MacroDefinitionRead(
-    serialization::MacroID ID, MacroDefinition *MD) {
+    serialization::PreprocessedEntityID ID, MacroDefinition *MD) {
   for (size_t i = 0, e = Listeners.size(); i != e; ++i)
     Listeners[i]->MacroDefinitionRead(ID, MD);
 }