[PATCH] mm: exit_mmap need not reset

exit_mmap resets various mm_struct fields, but the mm is well on its way out,
and none of those fields matter by this point.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>