systemd/systemd: fix boot on split-usr systems and cleanup meson options

systemd's meson.build looks up various systems utilties at build-time.
This wasn't a problem before, but as our buildroots are now usr-merged
we can no longer expect that meson's $PATH traversal results in a path
to a binary on non-usr-merge system. We need to state our expectations
explictly now.

This also removes some unneeded options. meson's get_option returns on
booleans without any default `true`.

Part-of: https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/6884
[ci:skip-build]: already built successfully in CI

extra-repos/systemd/systemd/APKBUILD

@@ -9,7 +9,7 @@
 pkgname=systemd
 pkgver=257.7
 _pkgver="musl-v${pkgver//_/-}-split-usr"
-pkgrel=6
+pkgrel=7
 pkgdesc="System and service manager"
 url="https://github.com/systemd/systemd"
 # ppc64le and s390x blocked by pmboostrap not supporting
@@ -168,36 +168,43 @@ build() {
 	sed -i "/'ENABLE_BOOTLOADER',/d" src/bless-boot/meson.build
 	sed -i "/systemd-bless-boot.service.in/,/},/ s/'ENABLE_BOOTLOADER', //" units/meson.build
 
+	# TODO: after usr-merge completion: remove hardcoded "-D*-path" options
 	abuild-meson \
 		-Dmode=release \
 		-Dsplit-bin=true \
 		-Dsplit-usr=true \
 		\
+		-Dquotaon-path=/usr/sbin/quotaon \
+		-Dquotacheck-path=/usr/sbin/quotacheck \
 		-Dkmod-path=/bin/kmod \
+		-Dkexec-path=/usr/sbin/kexec \
 		-Dsulogin-path=/sbin/sulogin \
+		-Dmount-path=/bin/mount \
+		-Dumount-path=/bin/umount \
+		-Dloadkeys-path=/usr/bin/loadkeys \
+		-Dsetfont-path=/usr/bin/setfont \
+		-Dnologin-path=/sbin/nologin \
 		\
 		-Ddebug-shell=/bin/ash \
 		-Dpolkit=enabled \
 		-Dpam=enabled \
 		-Dpamlibdir=/usr/lib/security \
 		-Dpamconfdir=/usr/lib/pam.d \
+		-Dsysupdated=enabled \
+		-Dimportd=enabled \
 		\
 		-Dbootloader=disabled \
 		-Dutmp=false \
 		-Dldconfig=false \
 		-Duserdb=false \
-		-Dimportd=enabled \
 		-Dhomed=disabled \
 		-Dnss-myhostname=false \
 		-Dnss-mymachines=disabled \
 		-Dnss-resolve=disabled \
 		-Dnss-systemd=false \
-		-Dsysext=true \
-		-Dsysupdated=enabled \
-		-Dsysusers=true \
 		-Dselinux=disabled \
 		\
-		-Dman=enabled\
+		-Dman=enabled \
 		-Dhtml=disabled \
 		\
 		-Dsystem-alloc-uid-min=101 \
@@ -209,16 +216,17 @@ build() {
 		-Dnobody-group=nobody \
 		\
 		-Ddefault-kill-user-processes=true \
-		-Dgshadow=false \
 		-Ddefault-locale=en_US.UTF-8 \
 		\
+		-Dgshadow=false \
+		-Didn=false \
+		-Dsysvinit-path="" \
+		\
 		-Ddefault-dns-over-tls=yes \
 		-Ddns-over-tls=openssl \
 		-Ddns-servers="9.9.9.10#dns10.quad9.net 149.112.112.10#dns10.quad9.net 2620:fe::10#dns10.quad9.net 2620:fe::fe:10#dns10.quad9.net" \
 		-Dntp-servers="0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 4.pool.ntp.org" \
 		\
-		-Didn=false \
-		-Dsysvinit-path="" \
 		-Dbpf-framework=enabled \
 		-Dvmlinux-h=provided \
 		-Dvmlinux-h-path="$(find /usr/src -path "/usr/src/linux-headers-*-stable/vmlinux.h" | sort -V | tail -n1)" \