_gcry_fast_wipememory2 should be changed to always just use explicit_memset when available:

#ifdef HAVE_EXPLICIT_MEMSET
explicit_memset (ptr, set, len);
#else
#ifdef HAVE_EXPLICIT_BZERO
if (set == 0)
    {
      explicit_bzero (ptr, len);
      return;
    }
#endif 

memset_ptr (ptr, set, len);
#endif

I'm not actually sure how workflow should be on the 'patches' interface at dev.gnupg.org.

Could you post this patch and your DCO to libgcrypt mailing-list?

Done ! Thanks.

Thanks !