main/postmarketos-base: don't depend on alpine-base

alpine-base directly depends on openrc. We have had different[1]
conversations[2] with upstream. And the main conclussion[3] has been:
if you want to do something different, just depend on things
yourself. This is indeed what docker images do. So let's just get the
things that we want from alpine base (quite some!), and ignore what we
don't want (openrc, busybox openrc and init packages). alpine-conf is
now a dependency of postmarketos-base-openrc, since it dependes on
openrc for calling setup-* scripts. postmarketos-base-systemd already
implements those needed.

Contrary to the first attempt[4], I have kept the dependency on
alpine-release. Changes to that are independent to the usr-merge, and
can be done as a follow-up.

This should allow to drop the fork of alpine-base currently in the
systemd-extra repository!

To this day, every single pmOS installation will have alpine-base in
the world file, which means that systemd installs will the forked
package until users specifically run "apk del alpine-base". We must
add this to release notes and to an edge blog post. Alternatively we
could have an empty package with a very high version providing
alpine-base.

[1] https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/63935
[2] https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/71686
[3] https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/71686#note_435428
[4] https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/5026

Part-of: https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/6375

main/postmarketos-base/APKBUILD

@@ -1,15 +1,23 @@
 pkgname=postmarketos-base
 pkgver=43
-pkgrel=2
+pkgrel=3
 pkgdesc="Meta package for minimal postmarketOS base"
 url="https://postmarketos.org"
 arch="noarch"
 license="GPL-3.0-or-later"
 makedepends="postmarketos-initramfs"
+# Several of these dependencies come from alpine - base, as the upstream
+# recommendation to not depend on openrc has been to copy them here:
+# https: // gitlab.alpinelinux.org/alpine/aports/-/merge_requests/71686#note_435428
 depends="
-	alpine-base
+	alpine-baselayout
+	alpine-release
+	apk-tools
+	busybox
+	busybox-suid
 	devicepkg-utils>=0.2.0
 	eudev
+	musl-utils
 	openssh-server-pam
 	postmarketos-keys
 	postmarketos-mvcfg
@@ -145,6 +153,9 @@ openrc() {
 		"
 	depends="
 		!systemd
+		alpine-conf
+		busybox-mdev-openrc
+		busybox-openrc
 		eudev-openrc
 		logbookd
 		logbookd-openrc

pmaports.cfg

@@ -15,7 +15,7 @@ supported_heimdall_depends=heimdall,android-tools
 [repo:systemd]
 pmaports_dir=systemd
 # Build forks of Alpine packages that support usr_merge
-bootstrap_1=abuild alpine-base
+bootstrap_1=abuild
 bootstrap_2=systemd
 # Build systemd related pkgs without deps on each other
 bootstrap_3=dbus linux-pam-pmos