Use None rather than Optional<T>() where possible.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175705 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/NSAPI.cpp b/lib/AST/NSAPI.cpp
index b06769e..a862630 100644
--- a/lib/AST/NSAPI.cpp
+++ b/lib/AST/NSAPI.cpp
@@ -75,7 +75,7 @@
       return MK;
   }
 
-  return Optional<NSStringMethodKind>();
+  return None;
 }
 
 Selector NSAPI::getNSArraySelector(NSArrayMethodKind MK) const {
@@ -133,7 +133,7 @@
       return MK;
   }
 
-  return Optional<NSArrayMethodKind>();
+  return None;
 }
 
 Selector NSAPI::getNSDictionarySelector(
@@ -219,7 +219,7 @@
       return MK;
   }
 
-  return Optional<NSDictionaryMethodKind>();
+  return None;
 }
 
 Selector NSAPI::getNSNumberLiteralSelector(NSNumberLiteralMethodKind MK,
@@ -282,14 +282,14 @@
       return MK;
   }
 
-  return Optional<NSNumberLiteralMethodKind>();
+  return None;
 }
 
 Optional<NSAPI::NSNumberLiteralMethodKind>
 NSAPI::getNSNumberFactoryMethodKind(QualType T) const {
   const BuiltinType *BT = T->getAs<BuiltinType>();
   if (!BT)
-    return Optional<NSAPI::NSNumberLiteralMethodKind>();
+    return None;
 
   const TypedefType *TDT = T->getAs<TypedefType>();
   if (TDT) {
@@ -363,7 +363,7 @@
     break;
   }
   
-  return Optional<NSAPI::NSNumberLiteralMethodKind>();
+  return None;
 }
 
 /// \brief Returns true if \param T is a typedef of "BOOL" in objective-c.