perf build: Always disable stack protection for BPF skeleton objects

perf build: Always disable stack protection for BPF skeleton objects

When the clang toolchain has stack protection enabled, the bpf
skeletons build fails with:

error: A call to built-in function '__stack_chk_fail' is not supported.

Since stack-protector makes no sense for the BPF bits, just unconditionally
disable it.

See also similar case at 878625e1c7a10dfbb1fdaaaae2c4d2a58fbce627

Signed-off-by: Federico Pellegrin <fede@evolware.org>
Link: https://lore.kernel.org/r/20250718041224.12389-1-fede@evolware.org
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Signed-off-by: Namhyung Kim <namhyung@kernel.org>