[PATCH] prio_tree: iterator + vma_prio_tree_next cleanup

[PATCH] prio_tree: iterator + vma_prio_tree_next cleanup

Currently we have:

	while ((vma = vma_prio_tree_next(vma, root, &iter,
                                        begin, end)) != NULL)
		do_something_with(vma);

Then iter,root,begin,end are all transfered unchanged to various functions.
 This patch hides them in struct iter instead.

It slightly lessens source, code size, and stack usage.  Patch compiles and
tested lightly.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Rajesh Venkatasubramanian <vrajesh@umich.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>