megapixels: simplify zbar fix

hosts/common/programs/default.nix

@@ -43,7 +43,6 @@
     ./libreoffice.nix
     ./lemoa.nix
     ./mako.nix
-    ./megapixels.nix
     ./mepo.nix
     ./mopidy.nix
     ./mpv.nix

hosts/common/programs/megapixels.nix

@@ -1,11 +0,0 @@
-{ pkgs, ... }:
-{
-  sane.programs.megapixels.package = pkgs.megapixels.override {
-    # megapixels uses zbar to read barcodes.
-    # zbar by default ships zbarcam-gtk and zbarcam-qt, neither of which megapixels needs.
-    # but the latter takes a dep on qt, which bloats the closure and the build, so disable this feature.
-    zbar = pkgs.zbar.override {
-      enableVideo = false;
-    };
-  };
-}

overlays/preferences.nix

@@ -81,4 +81,8 @@
       '';
     });
   };
+
+  # 2023/12/10: zbar barcode scanner: used by megapixels, frog.
+  # the video component does not cross compile (qt deps), but i don't need that.
+  zbar = super.zbar.override { enableVideo = false; };
 })