Make android_wakelock::Guard Send

[Niels-Be]

Im not sure if there currently is a way to do this.

But right now I think there is no way to use the android_wakelock::Guard across an await boundary because of its raw pointers stored in env.

I would like to acquire the wakelock, run some async tokio code and only after this is done release the lock.

I don't see why the attached thread needs to be stored inside the guard? The Java API should be thread save.

So can't you just attach a new env on release?