[core] Fix cpp macro logic.

(cherry picked from commit 5083cf55)

[core] Fix cpp macro logic.
e4ea4013 · Axel Naumann · ebf25ced · e4ea4013
Commit e4ea4013 authored 6 years ago by Axel Naumann
--- a/core/foundation/test/testNotFn.cxx
+++ b/core/foundation/test/testNotFn.cxx
 // Including functional for __cpp_lib_not_fn
 #include <functional>

-#ifdef __cpp_lib_not_fn
+#ifndef __cpp_lib_not_fn

 #include "ROOT/RNotFn.hxx"