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/0013-basic-Handle-musl-lack-of-NI_IDN.patch

@@ -0,0 +1,33 @@
+From 149d6484096f5eb328a625357aff063335902208 Mon Sep 17 00:00:00 2001
+From: "A. Wilcox" <AWilcox@Wilcox-Tech.com>
+Date: Sun, 18 Aug 2024 02:48:52 -0500
+Subject: [PATCH 13/34] basic: Handle musl lack of NI_IDN
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+Hopefully musl will grow support for IDN in the stub resolver soon, and
+this won't matter.
+
+This cannot be upstreamed.
+
+Signed-off-by: Alexander Miroshnichenko <alex@millerson.name>
+---
+ src/basic/socket-util.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
+index 6e304e840d2d..11a03f40dad1 100644
+--- a/src/basic/socket-util.c
++++ b/src/basic/socket-util.c
+@@ -36,7 +36,7 @@
+ #include "user-util.h"
+ #include "utf8.h"
+ 
+-#if ENABLE_IDN
++#if ENABLE_IDN && defined(NI_IDN)
+ #  define IDN_FLAGS NI_IDN
+ #else
+ #  define IDN_FLAGS 0
+-- 
+2.41.0
+