Rename cxx1z -> cxx17 across all diagnostic IDs.

llvm-svn: 310805
diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index ad82a44..d43c8c3 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -47,7 +47,7 @@
   // about using it as an extension.
   if (!S.getLangOpts().CPlusPlus1z && A.isCXX11Attribute() &&
       !A.getScopeName())
-    S.Diag(A.getLoc(), diag::ext_cxx1z_attr) << A.getName();
+    S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A.getName();
 
   FnScope->setHasFallthroughStmt();
   return ::new (S.Context) auto(Attr);