[clang][NFC] Remove old commented out code

`CheckedConversionKind` was converted to a scoped enum quite a while ago.

Author: Endilll

clang/include/clang/Sema/Sema.h

@@ -753,20 +753,6 @@ class Sema final : public SemaBase {
   void checkTypeSupport(QualType Ty, SourceLocation Loc,
                         ValueDecl *D = nullptr);
 
-  // /// The kind of conversion being performed.
-  // enum CheckedConversionKind {
-  //   /// An implicit conversion.
-  //   CCK_ImplicitConversion,
-  //   /// A C-style cast.
-  //   CCK_CStyleCast,
-  //   /// A functional-style cast.
-  //   CCK_FunctionalCast,
-  //   /// A cast other than a C-style cast.
-  //   CCK_OtherCast,
-  //   /// A conversion for an operand of a builtin overloaded operator.
-  //   CCK_ForBuiltinOverloadedOp
-  // };
-
   /// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit
   /// cast.  If there is already an implicit cast, merge into the existing one.
   /// If isLvalue, the result of the cast is an lvalue.