packages(ublock-origin): Document attempt at changing settings

This seemed to work to an extent but resulted in some weirdness with the
uBlock Origin from LibreWolf and the uBlock Origin from this package.

The actual setting didn't change even though it was disabled in the
interface. Re-enabling the checkbox and toggling it didn't change
anything either.

packages/ublock-origin.nix

@@ -2,6 +2,8 @@
   lib,
   stdenvNoCC,
   fetchurl,
+  unzip,
+  zip,
 }:
 
 stdenvNoCC.mkDerivation (finalAttrs: {
@@ -15,10 +17,27 @@ stdenvNoCC.mkDerivation (finalAttrs: {
 
   dontUnpack = true;
 
+  nativeBuildInputs = [
+    unzip
+    zip
+  ];
+
+  postPatch = ''
+    unzip "$src"
+
+    substituteInPlace ./js/vapi-background-ext.js \
+      --replace-fail "browser.dns instanceof Object" "false"
+
+    substituteInPlace ./js/background.js \
+      --replace-fail "cnameUncloakEnabled: true" "cnameUncloakEnabled: false"
+
+    zip -x env-vars -r ublock-origin.xpi *
+  '';
+
   installPhase = ''
     runHook preInstall
 
-    install -Dm644 "$src" "$out/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/uBlock0@raymondhill.net.xpi"
+    install -Dm644 ublock-origin.xpi "$out/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/uBlock0@raymondhill.net.xpi"
 
     runHook postInstall
   '';