linkIntoOwnPackage: handle share/man, share/doc consistently with nixpkgs

i.e. let stdenv move these to man/doc outputs, as appropriate

pkgs/by-name/trivial-builders/package.nix

@@ -35,16 +35,20 @@
       done
     '';
 
-  linkIntoOwnPackage = pkg: path: { wantMan ? null, ...}@args: let
+  linkIntoOwnPackage = pkg: path: { separateDoc ? null, separateMan ? null, ...}@args: let
     paths = if lib.isList path then path else [ path ];
     suffix = (lib.head paths) + (if paths != [ path ] then "-and-other-paths" else "");
-    wantMan' = if wantMan == null then
-      builtins.any (p: lib.hasPrefix "share/man" p || lib.hasPrefix "share/doc" p) paths
+    separateMan' = if separateMan == null then
+      builtins.any (p: lib.hasPrefix "share/man" p) paths
     else
-      wantMan;
+      separateMan;
+    separateDoc' = if separateDoc == null then
+      builtins.any (p: lib.hasPrefix "share/doc" p) paths
+    else
+      separateDoc;
   in
     runCommandLocalOverridable "${pkg.pname or pkg.name}-${suffix}" ({
-      outputs = [ "out" ] ++ lib.optionals wantMan' [ "man" ];
+      outputs = [ "out" ] ++ lib.optionals separateMan' [ "man" ] ++ lib.optionals separateDoc' [ "doc" ];
       inputs = pkg.all;
       pathsToLink = paths;
       configurePhase = ''
@@ -60,19 +64,6 @@
 
         runHook postConfigure
       '';
-      fixupPhase = ''
-        runHook preFixup
-
-        # move man-related outputs to man output
-        # TODO: doesn't nix do this for us automatically?
-        for item in share/doc share/man; do
-          if [ -e "$item" ]; then
-            moveToOutput "$item" "$man"
-          fi
-        done
-
-        runHook postFixup
-      '';
     } // args) ''
       tryLink() {
         local input=$1