Removed dead code from DiagnosticBuilder

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@371723 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/Diagnostic.h

@@ -1127,11 +1127,6 @@ public:
     Emit();
   }
 
-  /// Retrieve an empty diagnostic builder.
-  static DiagnosticBuilder getEmpty() {
-    return {};
-  }
-
   /// Forces the diagnostic to be emitted.
   const DiagnosticBuilder &setForceEmit() const {
     IsForceEmit = true;