systemd/systemd: re-enable BTF support

This fixes unprivileged nspawn.

Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/7898>

extra-repos/systemd/systemd/APKBUILD

@@ -9,10 +9,11 @@ maintainer="Casey Connolly <kcxt@postmarketos.org>"
 pkgname=systemd
 pkgver=259.1
 _pkgver="${pkgver/_/-}"
-pkgrel=0
+pkgrel=1
 pkgdesc="System and service manager"
 url="https://github.com/systemd/systemd"
-arch="all"
+# armhf: no linux-stable
+arch="all !armhf"
 license="MIT AND GPL-2.0-only AND LGPL-2.1-or-later"
 options="pmb:strict"
 
@@ -61,6 +62,7 @@ makedepends="
 	libselinux-dev
 	libxkbcommon-dev
 	linux-pam-dev
+	linux-stable-dev
 	llvm21
 	lz4-dev
 	meson
@@ -238,7 +240,8 @@ build() {
 		-Dntp-servers="0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 4.pool.ntp.org" \
 		\
 		-Dbpf-framework=enabled \
-		-Dvmlinux-h=disabled \
+		-Dvmlinux-h=provided \
+		-Dvmlinux-h-path="$(find /usr/src -path "/usr/src/linux-headers-*-stable/vmlinux.h" | sort -V | tail -n1)" \
 		build .
 	meson compile ${JOBS:+-j ${JOBS}} -C build
 }