define top-level attrs for getent, getconf

Note that currently getent is explicitly taken from "glibc.bin",
regardless of build configuration which this preserves for now.
(on non-musl anyway)

pkgs/os-specific/linux/systemd/default.nix

@@ -7,18 +7,13 @@
 , autoreconfHook, gettext, docbook_xsl, docbook_xml_dtd_42, docbook_xml_dtd_45
 , ninja, meson, python3Packages, glibcLocales
 , patchelf
-, musl-getent ? null
+, getent
 }:
 
 assert stdenv.isLinux;
 
 let
   pythonLxmlEnv = python3Packages.python.withPackages ( ps: with ps; [ python3Packages.lxml ]);
-  getent-bin =
-         if stdenv.hostPlatform.libc == "glibc" then stdenv.cc.libc.bin
-    else if stdenv.hostPlatform.isMusl then "${musl-getent}"
-    else throw "unsupported abi for systemd";
-  getent = "${getent-bin}/bin/getent";
 
 in
 
@@ -40,7 +35,7 @@ in
         ninja meson
         coreutils # meson calls date, stat etc.
         pythonLxmlEnv glibcLocales
-        patchelf getent-bin
+        patchelf getent
       ];
     buildInputs =
       [ linuxHeaders libcap kmod xz pam acl
@@ -114,7 +109,7 @@ in
         for i in src/remount-fs/remount-fs.c src/core/mount.c src/core/swap.c src/fsck/fsck.c units/emergency.service.in units/rescue.service.in src/journal/cat.c src/core/shutdown.c src/nspawn/nspawn.c src/shared/generator.c; do
           test -e $i
           substituteInPlace $i \
-            --replace /usr/bin/getent ${getent} \
+            --replace /usr/bin/getent ${getent}/bin/getent \
             --replace /sbin/swapon ${utillinux.bin}/sbin/swapon \
             --replace /sbin/swapoff ${utillinux.bin}/sbin/swapoff \
             --replace /sbin/fsck ${utillinux.bin}/sbin/fsck \