radix-tree: add missing cleanup.h

Add shared cleanup.h header for radix-tree testing tools.

Fixes build error found with kdevops [1]:

cc -I../shared -I. -I../../include -I../../../lib -g -Og -Wall
-D_LGPL_SOURCE -fsanitize=address -fsanitize=undefined   -c -o
radix-tree.o radix-tree.c
In file included from ../shared/linux/idr.h:1,
                 from radix-tree.c:18:
../shared/linux/../../../../include/linux/idr.h:18:10: fatal error:
linux/cleanup.h: No such file or directory
   18 | #include <linux/cleanup.h>
      |          ^~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [<builtin>: radix-tree.o] Error 1

[1] https://github.com/linux-kdevops/kdevops
https://github.com/linux-kdevops/linux-mm-kpd/
actions/runs/13971648496/job/39114756401

[[email protected]: remove unneeded header guards, per Sidhartha]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 6c8b0b8 ("perf/core: Simplify perf_pmu_register()")
Signed-off-by: Daniel Gomez <[email protected]>
Cc: Daniel Gomez <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Luis Chamberalin <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sidhartha Kumar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: dkruces

tools/testing/shared/linux/cleanup.h

@@ -0,0 +1,2 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include "../../../../include/linux/cleanup.h"