Remove @autoclosure and @noescape as decl attributes

Using these in declaration position has been deprecated and
removed in Swift 3.  These attributes were not being parsed and
contained deadweight diagnostics that should have been moved
when these attributes became type attributes.

lib/Serialization/Serialization.cpp

@@ -2078,15 +2078,6 @@ void Serializer::writeDeclAttribute(const DeclAttribute *DA) {
 #undef DEF_VER_TUPLE_PIECES
   }
 
-  case DAK_AutoClosure: {
-    auto *theAttr = cast<AutoClosureAttr>(DA);
-    auto abbrCode = DeclTypeAbbrCodes[AutoClosureDeclAttrLayout::Code];
-    AutoClosureDeclAttrLayout::emitRecord(Out, ScratchRecord, abbrCode,
-                                          theAttr->isImplicit(),
-                                          theAttr->isEscaping());
-    return;
-  }
-
   case DAK_ObjC: {
     auto *theAttr = cast<ObjCAttr>(DA);
     SmallVector<IdentifierID, 4> pieces;