openssh: add After dependencies on nss-user-lookup.target

Quoting 'man systemd.special':

  nss-user-lookup.target

    A target that should be used as synchronization point for all
    regular UNIX user/group name service lookups. [...] All services
    for which the availability of the full user/group database is
    essential should be ordered after this target, but not pull it
    in. All services which provide parts of the user/group database
    should be ordered before this target, and pull it in.

When no service providing parts of the user/group database exists and
thus pulls in the nss-user-lookup.target, this added dependency is a
no-op.

However, when such a service does exist, and e.g. modifies /etc/shadow
to change password or enable/disable certain accounts, it is essential
that no ssh connections are accepted until those changes are made.

(From OE-Core rev: 365b5490f3b12772ed57a6bcfd1e0e8a91185afc)

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-connectivity/openssh/openssh/sshd.service

@@ -2,6 +2,7 @@
 Description=OpenSSH server daemon
 Wants=sshdgenkeys.service
 After=sshdgenkeys.service
+After=nss-user-lookup.target
 
 [Service]
 Environment="SSHD_OPTS="

meta/recipes-connectivity/openssh/openssh/sshd.socket

@@ -1,6 +1,7 @@
 [Unit]
 Conflicts=sshd.service
 Wants=sshdgenkeys.service
+After=nss-user-lookup.target
 
 [Socket]
 ExecStartPre=@BASE_BINDIR@/mkdir -p /var/run/sshd