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/0009-test-Change-expected-message-for-unhappy-sysusers.patch

@@ -0,0 +1,26 @@
+From 8356019ca35e557a98fbb5ccfbc5b60f64ea38d5 Mon Sep 17 00:00:00 2001
+From: "A. Wilcox" <AWilcox@Wilcox-Tech.com>
+Date: Sun, 18 Aug 2024 02:34:45 -0500
+Subject: [PATCH 09/34] test: Change expected message for unhappy sysusers
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+The error string for ERANGE is different between musl and glibc.
+
+This cannot be upstreamed.
+
+Signed-off-by: Alexander Miroshnichenko <alex@millerson.name>
+---
+ test/test-sysusers/unhappy-1.expected-err | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/test/test-sysusers/unhappy-1.expected-err b/test/test-sysusers/unhappy-1.expected-err
+index f6b1b3c5e6f0..17da5bd2537b 100644
+--- a/test/test-sysusers/unhappy-1.expected-err
++++ b/test/test-sysusers/unhappy-1.expected-err
+@@ -1 +1 @@
+- Failed to parse UID: '9999999999': Numerical result out of range
++ Failed to parse UID: '9999999999': Result not representable
+-- 
+2.41.0
+