kmemleak: use rbtree instead of prio tree

kmemleak: use rbtree instead of prio tree

kmemleak uses a tree where each node represents an allocated memory object
in order to quickly find out what object a given address is part of.
However, the objects don't overlap, so rbtrees are a better choice than
prio tree for this use.  They are both faster and have lower memory
overhead.

Tested by booting a kernel with kmemleak enabled, loading the
kmemleak_test module, and looking for the expected messages.

Signed-off-by: Michel Lespinasse <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Woodhouse <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Tested-by: Catalin Marinas <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>