The build fails first of all because it cannot find the function body
for __builtin_memset. In glibc 2.26 this is available via inclusion of
string.h.
Another failure was that UINT64_MAX wasn't available in staging/tools.c,
which is fixed again by inclusion of stdint.h.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @nckx
