Fix build after r319688: s/CPlusPlus1z/CPlusPlus17/

llvm-svn: 319690
diff --git a/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
index c2129e3..67c0063 100644
--- a/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
@@ -18,7 +18,7 @@
 namespace modernize {
 
 void UnaryStaticAssertCheck::registerMatchers(MatchFinder *Finder) {
-  if (!getLangOpts().CPlusPlus1z)
+  if (!getLangOpts().CPlusPlus17)
     return;
 
   Finder->addMatcher(staticAssertDecl().bind("static_assert"), this);