steam: actually propagate flags to the runtime, now from chrootenv wrapper

Example: instead of

(steamPackages.override { newStdcpp = true; }).steam-chrootenv

(which wasn't working anyway) you now do just:

steam.override { newStdcpp = true; }

pkgs/games/steam/chrootenv.nix

@@ -1,6 +1,9 @@
 { lib, buildFHSUserEnv, steam
-, withJava   ? false
+, withJava ? false
 , withPrimus ? false
+, nativeOnly ? false
+, runtimeOnly ? false
+, newStdcpp ? false
 }:
 
 buildFHSUserEnv {
@@ -20,7 +23,7 @@ buildFHSUserEnv {
       # Needed by gdialog, including in the steam-runtime
       perl
     ]
-    ++ lib.optional withJava   jdk
+    ++ lib.optional withJava jdk
     ++ lib.optional withPrimus primus
     ;
 
@@ -38,7 +41,9 @@ buildFHSUserEnv {
       gst_all_1.gst-plugins-ugly
       libdrm
 
-      steamPackages.steam-runtime-wrapped
+      (steamPackages.steam-runtime-wrapped.override {
+        inherit nativeOnly runtimeOnly newStdcpp;
+      })
     ];
 
   extraBuildCommands = ''

pkgs/games/steam/default.nix

@@ -1,17 +1,11 @@
-{ pkgs, newScope
+{ pkgs, newScope }:
-, nativeOnly ? false
-, runtimeOnly ? false
-, newStdcpp ? false
-}:
 
 let
   callPackage = newScope self;
 
   self = rec {
     steam-runtime = callPackage ./runtime.nix { };
-    steam-runtime-wrapped = callPackage ./runtime-wrapped.nix {
+    steam-runtime-wrapped = callPackage ./runtime-wrapped.nix { };
-      inherit nativeOnly runtimeOnly newStdcpp;
-    };
     steam = callPackage ./steam.nix { };
     steam-chrootenv = callPackage ./chrootenv.nix { };
     steam-fonts = callPackage ./fonts.nix { };