openssh: add backported header file include

Backport upstream patch to add a missing header.  The patch says it is
for systemd, but I am seeing build issues when building openssh with
clang and musl.  The issue being seen is:
 #warning usage of non-standard #include <sys/cdefs.h> is deprecated
And similar deprecated warnings.  This patch resolves the issue.

Original patch can be found at
88351eca17

This issue was introduced with OE-Core 1c9d3c22718bf49ae85c2d06e0ee60ebdc2fd0c1
1c9d3c2271

Patch suggested by Khem Raj.

(From OE-Core rev: ae4064a8a60b60bee8a32a454e8784fcf1ecd318)

Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/recipes-connectivity/openssh/openssh/0001-Fix-missing-header-for-systemd-notification.patch

@@ -0,0 +1,27 @@
+From 88351eca17dcc55189991ba60e50819b6d4193c1 Mon Sep 17 00:00:00 2001
+From: 90 <hi@90.gripe>
+Date: Fri, 5 Apr 2024 19:36:06 +0100
+Subject: [PATCH] Fix missing header for systemd notification
+
+Upstream-Status: Backport [88351eca17dcc55189991ba60e50819b6d4193c1]
+Signed-off-by: Jon Mason <jdmason@kudzu.us>
+
+---
+ openbsd-compat/port-linux.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/openbsd-compat/port-linux.c b/openbsd-compat/port-linux.c
+index df7290246df6..4c024c6d2d61 100644
+--- a/openbsd-compat/port-linux.c
++++ b/openbsd-compat/port-linux.c
+@@ -33,6 +33,7 @@
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <time.h>
++#include <unistd.h>
+ 
+ #include "log.h"
+ #include "xmalloc.h"
+-- 
+2.39.2
+

meta/recipes-connectivity/openssh/openssh_9.6p1.bb

@@ -28,6 +28,7 @@ SRC_URI = "http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-${PV}.tar
            file://0001-notify-systemd-on-listen-and-reload.patch \
            file://CVE-2024-6387.patch \
            file://CVE-2024-39894.patch \
+           file://0001-Fix-missing-header-for-systemd-notification.patch \
            "
 SRC_URI[sha256sum] = "910211c07255a8c5ad654391b40ee59800710dd8119dd5362de09385aa7a777c"