Stable/15 bootstrap build error on aarch64

From: Dima Panov <fluffy_at_FreeBSD.org>
Date: Mon, 15 Sep 2025 08:47:23 UTC
Hello!

Something changed in stable/15 between 89e9d3ca6 and deaa609d0 which caused a bootstrap build error in poudriere

--- _bootstrap-tools-lib/clang/libllvmminimal ---
/opt/poudriere/jails/150aarch64/usr/src/contrib/llvm-project/llvm/lib/Support/xxhash.cpp:60:10: fatal error: arm_neon.h file not found
60 | #include
| ^~~~~~~~~~~~
1 error generated.
*** [Support/xxhash.o] Error code 1

make[3]: stopped making "all" in /opt/poudriere/jails/150aarch64/usr/src/lib/clang/libllvmminimal
make[3]: 1 error

--
Dima. (desktop, kde, x11, office, ports-secteam)@FreeBSD team
(fluffy@FreeBSD.org, https://t.me/FluffyBSD)