Added LLVM_FALLTHROUGH to address warning: this statement may fall through. NFC.

llvm-svn: 304650
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index c19812e..17d0ce6 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -736,6 +736,7 @@
             if (!HasFoldFailureDiagnostic)
               break;
             // We've already failed to fold something. Keep that diagnostic.
+            LLVM_FALLTHROUGH;
           case EM_ConstantExpression:
           case EM_PotentialConstantExpression:
           case EM_ConstantExpressionUnevaluated:
@@ -10374,6 +10375,7 @@
     }
 
     // OffsetOf falls through here.
+    LLVM_FALLTHROUGH;
   }
   case Expr::OffsetOfExprClass: {
     // Note that per C99, offsetof must be an ICE. And AFAIK, using
@@ -10476,6 +10478,7 @@
       return Worst(LHSResult, RHSResult);
     }
     }
+    LLVM_FALLTHROUGH;
   }
   case Expr::ImplicitCastExprClass:
   case Expr::CStyleCastExprClass: