fix compilation error on ia64.
This patch fixes the following compilation error.
Since struct page_list_head is defined in mm.h, sched.h needs mm.h.
Other circular inclusions are sorted out.
In file included from xen/include/asm-ia64/linux-xen/asm/smp.h:50,
from
[IA64] shrink ia64 struct page_info.
This patch is the ia64 counter part of 19107:0858f961c77a,
19132:5848b49b74fc and 19136:162cdb596b9a.
This patch shrink ia64 struct page_info and rearrange its members.
The shrinking is made compile time option in config.h with default off
becuase physical
