numa_get_mems_allowed bug

Happy Thanksgiving to all.  It appears that numa_get_mems_allowed()
does not use the MPOL_F_MEMS_ALLOWED flag.  The return value I receive
when calling this function is an empty nodemask.  I've put together a
hack that uses MPOL_F_MEMS_ALLOWED, and I get the correct nodemask.
The hack I put together does not do the proper error checking that is
performed by getpol().  I'm not sure what is the best patch to fix the
issue.  Perhaps add a third argument to getpol() that accepts an
unsigned long flag?

Cheers,
--Michael