implement the alias attirbute (in both Sema and Codegen)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@52092 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index f91cbf4..a86bc6b 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -319,6 +319,7 @@
   void HandleExtVectorTypeAttribute(TypedefDecl *d, AttributeList *rawAttr);
   
   void HandleAlignedAttribute(Decl *d, AttributeList *rawAttr);
+  void HandleAliasAttribute(Decl *d, AttributeList *rawAttr);
   void HandlePackedAttribute(Decl *d, AttributeList *rawAttr);
   void HandleAnnotateAttribute(Decl *d, AttributeList *rawAttr);
   void HandleNoReturnAttribute(Decl *d, AttributeList *rawAttr);