am 391915d2: Update cstddef after clang r207606.

* commit '391915d2237ebf087dc4d5609484d6ebdb153fb9':
  Update cstddef after clang r207606.
diff --git a/include/cstddef b/include/cstddef
index 0030ec2..c3ca64a 100644
--- a/include/cstddef
+++ b/include/cstddef
@@ -35,12 +35,6 @@
 
 #include <__config>
 
-#ifdef __GLIBC__
-#define __need_NULL
-#define __need_ptrdiff_t
-#define __need_size_t
-#endif  // __GLIBC__
-
 #include <stddef.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)