overlays: patch firefox with .diff file from aur/firefox-xdg

nixos/packages/overlays/firefox.nix

@@ -0,0 +1,24 @@
+
+{ ... }:
+
+{
+  nixpkgs = {
+    overlays = [
+      (final: prev:
+        {
+            firefox-unwrapped = prev.firefox-unwrapped.overrideAttrs (old: {
+            # Firefox but with .mozilla moved to .config/mozilla
+            # .patch file from aur/firefox-xdg
+            # dont actually use this, =.=
+            patches = (old.patches or []) ++ [
+              (prev.fetchpatch {
+                url = "https://aur.archlinux.org/cgit/aur.git/plain/firefox-xdg-support.diff?h=firefox-xdg";
+                hash = "sha256-9LibQ+dIZ7MeTcuKEuJ42AW8m7Q7mVBwT4KyGeJTJ88=";
+              })
+            ];
+          });
+        }
+      )
+    ];
+  };
+}