rsyslog: Move systemd check

pkgs/tools/system/rsyslog/default.nix

···
 
   buildInputs = [
     pkgconfig libestr json_c zlib pythonPackages.docutils
-    krb5 systemd jemalloc mysql postgresql libdbi net_snmp libuuid curl gnutls
+    krb5 jemalloc mysql postgresql libdbi net_snmp libuuid curl gnutls
     libgcrypt liblognorm openssl librelp libgt liblogging libnet hadoop rdkafka
     libmongo-client czmq rabbitmq-c hiredis
-  ];
+  ] ++ stdenv.lib.optional stdenv.isLinux systemd;
 
   configureFlags = [
     "--sysconfdir=/etc"

pkgs/top-level/all-packages.nix

···
     libgcrypt = libgcrypt_1_6;
     czmq = null; # Currently Broken
     hadoop = null; # Currently Broken
-    systemd = if stdenv.isLinux then systemd else null;
   };
 
   rsyslog-light = callPackage ../tools/system/rsyslog {