systemd: fix libnss-mymachines packaging

By removing libnss_mymachines.so.2 from FILES:${PN}-container it
correctly gets packaged into libnss-mymachines, just like the other
libnss-* components, due to PACKAGES_DYNAMIC.

To make up for the missing lib in the container package, I added
libnss-mymachines to RDEPENDS:${PN}-container. As I understand it,
the lib should be installed even without this if anything from the
container package links against it. But since I don't know if there
was a special reason to explicitly add it to the container files list,
like something using dlopen to load the lib, it seemd to be the
safest option.

(From OE-Core rev: 90f143984732ba0453c2d3a734eeb4d1a289269b)

Signed-off-by: Florian Wickert <fw@ferncast.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd_254.4.bb

@@ -534,7 +534,6 @@ FILES:${PN}-container = "${sysconfdir}/dbus-1/system.d/org.freedesktop.import1.c
                          ${exec_prefix}/lib/tmpfiles.d/systemd-nspawn.conf \
                          ${exec_prefix}/lib/tmpfiles.d/README \
                          ${systemd_system_unitdir}/systemd-nspawn@.service \
-                         ${libdir}/libnss_mymachines.so.2 \
                          ${datadir}/dbus-1/system-services/org.freedesktop.import1.service \
                          ${datadir}/dbus-1/system-services/org.freedesktop.machine1.service \
                          ${datadir}/dbus-1/system.d/org.freedesktop.import1.conf \
@@ -543,6 +542,8 @@ FILES:${PN}-container = "${sysconfdir}/dbus-1/system.d/org.freedesktop.import1.c
                          ${datadir}/polkit-1/actions/org.freedesktop.machine1.policy \
                         "
 
+RDEPENDS:${PN}-container = "libnss-mymachines"
+
 # "machinectl import-tar" uses "tar --numeric-owner", not supported by busybox.
 RRECOMMENDS:${PN}-container += "\
                          ${PN}-journal-gatewayd \