[libc++] NFC: Normalize `#endif //` comment indentation

GitOrigin-RevId: 4cd6ca102a94e1b64ba3f940cc26b4d7b2b82964
diff --git a/include/cstring b/include/cstring
index 8bc96a0..6781415 100644
--- a/include/cstring
+++ b/include/cstring
@@ -93,4 +93,4 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif  // _LIBCPP_CSTRING
+#endif // _LIBCPP_CSTRING