[PATCH] mempolicy.c compile fix, make sure BITS_PER_BYTE is defined

[PATCH] mempolicy.c compile fix, make sure BITS_PER_BYTE is defined

Gar..

mm/mempolicy.c: In function 'get_nodes':
mm/mempolicy.c:527: error: 'BITS_PER_BYTE' undeclared (first use in this function)
mm/mempolicy.c:527: error: (Each undeclared identifier is reported only once
mm/mempolicy.c:527: error: for each function it appears in.)

About to retry a build with the below patch which should do the trick.
(How did this *ever* build?)

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>