Now that C++17 is official (https://www.iso.org/standard/68564.html), start changing the C++1z terminology over to C++17. NFC intended, these are all mechanical changes.

llvm-svn: 319688
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index f7b3b33..6126cc5 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -170,7 +170,7 @@
     C.Deallocate(data().getBases());
 
   if (NumBases) {
-    if (!C.getLangOpts().CPlusPlus1z) {
+    if (!C.getLangOpts().CPlusPlus17) {
       // C++ [dcl.init.aggr]p1:
       //   An aggregate is [...] a class with [...] no base classes [...].
       data().Aggregate = false;