Re-apply the series of commits to remove redundantly-serialized conformances.

I can't actually reproduce the buildbot failure that happened last night, so
hopefully it will (a) happen again, so I can investigate, or (b) not happen
again.

Swift SVN r22230

include/swift/Serialization/ModuleFile.h

@@ -340,14 +340,6 @@ private:
   /// If the record at the cursor is not a pattern, returns null.
   Pattern *maybeReadPattern();
 
-  /// Read a referenced conformance, such as the underlying conformance for a
-  /// specialized or inherited protocol conformance.
-  ProtocolConformance *
-  readReferencedConformance(ProtocolDecl *proto,
-                            serialization::DeclID typeID,
-                            serialization::ModuleID moduleID,
-                            llvm::BitstreamCursor &Cursor);
-
   GenericParamList *maybeGetOrReadGenericParams(serialization::DeclID contextID,
                                                 DeclContext *DC,
                                                 llvm::BitstreamCursor &Cursor);
@@ -386,9 +378,6 @@ private:
                         serialization::DeclID didSet);
 
 public:
-  /// Returns the decl context with the given ID, deserializing it if needed.
-  DeclContext *getDeclContext(serialization::DeclID DID);
-
   /// Loads a module from the given memory buffer.
   ///
   /// \param moduleInputBuffer A memory buffer containing the serialized module
@@ -511,6 +500,9 @@ public:
   Decl *getDecl(serialization::DeclID DID,
                 Optional<DeclContext *> ForcedContext = {});
 
+  /// Returns the decl context with the given ID, deserializing it if needed.
+  DeclContext *getDeclContext(serialization::DeclID DID);
+
   /// Returns the appropriate module for the given ID.
   Module *getModule(serialization::ModuleID MID);
 
@@ -535,6 +527,14 @@ public:
   Optional<ProtocolConformance *>
   maybeReadConformance(Type conformingType, llvm::BitstreamCursor &Cursor);
 
+  /// Read a referenced conformance, such as the underlying conformance for a
+  /// specialized or inherited protocol conformance.
+  ProtocolConformance *
+  readReferencedConformance(ProtocolDecl *proto,
+                            serialization::DeclID typeID,
+                            serialization::ModuleID moduleID,
+                            llvm::BitstreamCursor &Cursor);
+
   /// Reads a generic param list from \c DeclTypeCursor.
   ///
   /// If the record at the cursor is not a generic param list, returns null