[Bug libstdc++/69881] with gcc-6 of today building gcc-4.9 fails

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69881

--- Comment #3 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
or 

#undef all these __need_XXX before including stddef.h,
after all it is a bit bogus ghat gmp.h does:

#define __need_size_t  /* tell gcc stddef.h we only want size_t */
#include <cstddef>     /* for size_t */

is cstddef supposed to honor __need_size_t at all?