symlinkJoin: allow arbitrary additional attributes

pkgs/build-support/trivial-builders.nix

@@ -48,17 +48,15 @@ rec {
 
   # Create a forest of symlinks to the files in `paths'.
   symlinkJoin =
-    { name
+    args@{ name
          , paths
          , preferLocalBuild ? true
          , allowSubstitutes ? false
          , postBuild ? ""
-    , buildInputs ? []
-    , meta ? {}
+         , ...
          }:
     runCommand name
-      { inherit paths preferLocalBuild allowSubstitutes buildInputs meta;
-      }
+      (removeAttrs args [ "name" "postBuild" ])
       ''
         mkdir -p $out
         for i in $paths; do