nix: fix gomobile builds requiring Android SDK

This works fine on `x86_64`, but will fail when used on `aarch64`.

Issue: https://github.com/status-im/status-react/issues/12794

Signed-off-by: Jakub Sokołowski <jakub@status.im>

nix/overlay.nix

@@ -42,6 +42,8 @@ in {
     allowHigher = true;
   };
   gomobile = super.gomobile.override {
+    # FIXME: No Android SDK packages for aarch64-darwin.
+    withAndroidPkgs = stdenv.system != "aarch64-darwin";
     androidPkgs = self.androidEnvCustom.compose;
   };