erlang: Build with systemd support

That way 'epmd' can be started by systemd using socket
activation. This is important to have when there is more than one
Erlang system used on the same host.

Support for this exists since 17.0:
b7c95eabf6

Configure flag was added in 17.1:
12cd5e5b39

pkgs/development/interpreters/erlang/generic-builder.nix

@@ -3,6 +3,7 @@
 , openjdk ? null # javacSupport
 , unixODBC ? null # odbcSupport
 , libGLU_combined ? null, wxGTK ? null, wxmac ? null, xorg ? null # wxSupport
+, withSystemd ? stdenv.isLinux, systemd # systemd support in epmd
 }:
 
 { baseName ? "erlang"
@@ -53,6 +54,7 @@ in stdenv.mkDerivation ({
     ++ optionals wxSupport wxPackages2
     ++ optionals odbcSupport odbcPackages
     ++ optionals javacSupport javacPackages
+    ++ optional withSystemd systemd
     ++ optionals stdenv.isDarwin (with pkgs.darwin.apple_sdk.frameworks; [ Carbon Cocoa ]);
 
   debugInfo = enableDebugInfo;
@@ -82,6 +84,7 @@ in stdenv.mkDerivation ({
     ++ optional javacSupport "--with-javac"
     ++ optional odbcSupport "--with-odbc=${unixODBC}"
     ++ optional wxSupport "--enable-wx"
+    ++ optional withSystemd "--enable-systemd"
     ++ optional stdenv.isDarwin "--enable-darwin-64bit";
 
   # install-docs will generate and install manpages and html docs