lib/rbtree: enable userland test suite for rbtree related data structure

lib/rbtree: enable userland test suite for rbtree related data structure

Patch series "lib/interval_tree: add some test cases and cleanup", v2.

Since rbtree/augmented tree/interval tree share similar data structure,
besides new cases for interval tree, this patch set also does cleanup for
others.

This patch (of 7):

Currently we have some tests for rbtree related data structure, e.g.
rbtree, augmented rbtree, interval tree, in lib/ as kernel module.

To facilitate the test and debug for those fundamental data structure,
this patch enable those tests in userland.

Link: https://lkml.kernel.org/r/20250310074938.26756-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20250310074938.26756-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michel Lespinasse <michel@lespinasse.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>