The perf build includes arm64's unistd.h, but its dependent header
unistd_64.h is missing.

As suggested by Arnd in [1]:

  "I would suggest using the same method across all architectures:
   either we figure out how to use the generated headers on all of them
   (including x86, which uses yet another method), or we just stick with
   the old asm-generic/unistd.h copy and use that on arm64 as well."

A dynamic approach (e.g., make headers_install) may be explored later to
generate headers for tools, but that will need consensus from the tools
maintainers.  In the meantime, this series provides a quick fix by using
the asm-generic/unistd.h copy for arm64.

[1] https://lore.kernel.org/linux-arm-kernel/20251222173653.GF9788@e132581.arm.com/T/#m69a051aae5e53a65f9b10e1d13f67b3e92f4bbc7

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
Changes in v3:
- Changed to include asm-generic/unistd.h copy (Arnd).
- Removed check due to divergence between the kernel and tools.
- Link to v2: https://lore.kernel.org/r/20251210-perf_fix_syscall_header-v2-0-b18b6016e0ea@arm.com

Changes in v2:
- Added a consistency check (Ian).
- Rebased on the latest perf-tools-next.
- Link to v1: https://lore.kernel.org/r/20251204-perf_fix_syscall_header-v1-0-b8e27f74ed6a@arm.com

---
Leo Yan (3):
      tools headers: Go back to include asm-generic/unistd.h for arm64
      Revert "perf tools: Fix arm64 build by generating unistd_64.h"
      tools headers: Don't check arm64's unistd.h

 tools/arch/arm64/include/uapi/asm/unistd.h | 24 +++++++++++++++++++++++-
 tools/lib/perf/Makefile                    | 14 ++------------
 tools/perf/Makefile.config                 |  1 -
 tools/perf/check-headers.sh                |  1 -
 4 files changed, 25 insertions(+), 15 deletions(-)
---
base-commit: cb015814f8b6eebcbb8e46e111d108892c5e6821
change-id: 20251203-perf_fix_syscall_header-e280fa931d44

Best regards,
-- 
Leo Yan <leo.yan@arm.com>