Add a CastKind enum to CastExpr. Right now it's not used for much but it will be :)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77650 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 9edf259..b311cf7 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -3075,8 +3075,8 @@
   if (CheckCastTypes(SourceRange(LParenLoc, RParenLoc), castType, castExpr))
     return ExprError();
   return Owned(new (Context) CStyleCastExpr(castType.getNonReferenceType(),
-                                            castExpr, castType,
-                                            LParenLoc, RParenLoc));
+                                            CastExpr::CK_Unknown, castExpr, 
+                                            castType, LParenLoc, RParenLoc));
 }
 
 /// Note that lhs is not null here, even if this is the gnu "x ?: y" extension.