tree: remove unused argument from RB_NEXT()/RB_PREV()

[kp]

Summary

5fce408cc44c737267aaaf0dcecd3454ba9089cd stopped using the middle
argument to these macros. Remove it entirely and update all users of it,
to make it easier to deal with 'unused parameter' warnings.

The bulk of this change is a mechanical substitution (with Coccinelle):

@@ expression A,B,C; @@
(

• RB_NEXT(A, B, C)

+ RB_NEXT(A, C)
)
@@ expression A,B,C; @@
(

• RB_PREV(A, B, C)

+ RB_PREV(A, C)
)

[kp]

Thinking about this again, it's probably not the right way to go because there may be out-of-tree (userspace) consumers of RB_NEXT/RB_PREV, and they'd break.

[emaste]

Request an exp-run and see if any ports are affected?

[pauamma_gundo.com]

Manual page question/correction

share/man/man3/tree.3

165

Currently, the rendered tree(3) has

struct TYPE *
RB_NEXT(NAME, RB_HEAD *head, struct TYPE *elm);

So this looks like you're removing the last argument, not the middle one.

167

Same as above.