sys-apps/systemd: add v256.5 with musl libc patches

- https://code.atwilcox.tech/sphen/scaly/systemd
- https://catfox.life/2024/09/05/porting-systemd-to-musl-libc-powered-linux/

sys-apps/systemd/files/0024-basic-Use-sys-prctl.h-vs-linux-prctl.h.patch

@@ -0,0 +1,29 @@
+From 698acf92b1ce0c182318c02a87b0f874e5e79b2f Mon Sep 17 00:00:00 2001
+From: "A. Wilcox" <AWilcox@Wilcox-Tech.com>
+Date: Sun, 18 Aug 2024 03:12:10 -0500
+Subject: [PATCH 24/34] basic: Use <sys/prctl.h> vs <linux/prctl.h>
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+Signed-off-by: A. Wilcox <AWilcox@Wilcox-Tech.com>
+Signed-off-by: Alexander Miroshnichenko <alex@millerson.name>
+---
+ src/basic/missing_prctl.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/basic/missing_prctl.h b/src/basic/missing_prctl.h
+index 2c9f9f6c50ff..ed065828d1ae 100644
+--- a/src/basic/missing_prctl.h
++++ b/src/basic/missing_prctl.h
+@@ -1,7 +1,7 @@
+ /* SPDX-License-Identifier: LGPL-2.1-or-later */
+ #pragma once
+ 
+-#include <linux/prctl.h>
++#include <sys/prctl.h>
+ 
+ #include "macro.h"
+ 
+-- 
+2.41.0
+