* Updated Syncthing to v1.18.3-rc.1
* Allow building on windows
* Update NDK
* Revert "Updated Syncthing to v1.18.3-rc.1"
This reverts commit 377482c855.
- Use ndk 21 due to Go bug: https://github.com/golang/go/issues/42655
- Use pre-built clang binaries instead of building ourselves
- Build syncthing when creating container to prepopulate modules