[BUG] perf tools: Build failure in v6.16-rc1

[Namhyung Kim <namhyung@kernel.org>]

Hello,

I've updated the perf-tools-next to v6.16-rc1 and found a build error
like below on alpine linux 3.18.

  In file included from bench/futex.c:6:
  /usr/include/sys/prctl.h:88:8: error: redefinition of 'struct prctl_mm_map'
     88 | struct prctl_mm_map {
        |        ^~~~~~~~~~~~
  In file included from bench/futex.c:5:
  /linux/tools/include/uapi/linux/prctl.h:134:8: note: originally defined here
    134 | struct prctl_mm_map {
        |        ^~~~~~~~~~~~
  make[4]: *** [/linux/tools/build/Makefile.build:86: /build/bench/futex.o] Error 1

git bisect says it's the first commit introduced the failure.

commit 60035a3981a7f9d965df81a48a07b94e52ccd54f
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Wed Apr 16 18:29:19 2025 +0200

    tools/perf: Allow to select the number of hash buckets
    
    Add the -b/ --buckets argument to specify the number of hash buckets for
    the private futex hash. This is directly passed to
        prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, buckets, immutable)
    
    and must return without an error if specified. The `immutable' is 0 by
    default and can be set to 1 via the -I/ --immutable argument.
    The size of the private hash is verified with PR_FUTEX_HASH_GET_SLOTS.
    If PR_FUTEX_HASH_GET_SLOTS failed then it is assumed that an older
    kernel was used without the support and that the global hash is used.
    
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Link: https://lore.kernel.org/r/20250416162921.513656-20-bigeasy@linutronix.de

Thanks,
Namhyung