Build mbsync with with OAUTH2 support

overlays/cyrus-sasl-oauth2.nix

@@ -0,0 +1,24 @@
+{ config, lib, pkgs, inputs, ... }:
+
+let
+  cyrus-sasl-xoauth2 = with pkgs;
+    stdenv.mkDerivation {
+      name = "cyrus-sasl-xoauth2";
+      src = inputs.cyrus-sasl-xoauth2;
+      nativeBuildInputs =
+        [ autoreconfHook inputs.nixpkgs.legacyPackages."${system}".cyrus_sasl ];
+    };
+
+in {
+  nixpkgs.overlays = [
+    (final: prev: {
+      patched-cyrus-sasl-oauth2 = prev.cyrus_sasl.overrideAttrs (div: rec {
+        postInstall = ''
+          for lib in ${cyrus-sasl-xoauth2}/lib/sasl2/*; do
+            ln -sf $lib $out/lib/sasl2/
+          done
+        '';
+      });
+    })
+  ];
+}