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/0003-fileio-Disable-use-of-disabling-write-buffer.patch

@@ -0,0 +1,34 @@
+From e14c8f31006bda5cdc2e42d9f7dcc9c00bca1f06 Mon Sep 17 00:00:00 2001
+From: "A. Wilcox" <AWilcox@Wilcox-Tech.com>
+Date: Sun, 18 Aug 2024 02:02:34 -0500
+Subject: [PATCH 03/34] fileio: Disable use of disabling write buffer
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+It doesn't work properly on musl and it breaks more than it fixes.
+
+This cannot be sent upstream.
+
+Signed-off-by: Alexander Miroshnichenko <alex@millerson.name>
+---
+ src/basic/fileio.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/basic/fileio.c b/src/basic/fileio.c
+index 523378177fb7..2e2875ec171c 100644
+--- a/src/basic/fileio.c
++++ b/src/basic/fileio.c
+@@ -311,8 +311,8 @@ int write_string_file_ts_at(
+         if (r < 0)
+                 goto fail;
+ 
+-        if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
+-                setvbuf(f, NULL, _IONBF, 0);
++        /*if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
++                setvbuf(f, NULL, _IONBF, 0);*/
+ 
+         r = write_string_stream_ts(f, line, flags, ts);
+         if (r < 0)
+-- 
+2.41.0
+