Merge branch 'old-cpp' into 'master'

Fix lack of nullptr for older C++

See merge request redox-os/relibc!1410

src/header/bits_null/cbindgen.toml

@@ -11,7 +11,11 @@ language = "C"
 no_includes = true
 after_includes = """
 #ifdef __cplusplus
+#if __cplusplus >= 201103L
   #define NULL nullptr
+#else
+  #define NULL 0L
+#endif
 #else
   #define NULL ((void *)0)
 #endif