Add support for writing AIDL FMQs

[mlehtima]

No description provided.

[mlehtima]

Will be used in sailfishos/sensorfw#31

[monich]

from the first glance it seems more appropriate to implement this as a protocol specific feature via yet another GBinderRpcProtocol callback.

I generally don't like "virtialuzation" by means of ifs, and on top of that, relying on protocol naming conventions is imo too fragile, especially when those conventions are not clearly spelled out and not guaranteed to be followed.

let me think...

[mlehtima]

@monich I now changed appending fmq descriptor to go via protocol callback. I didn't know if I should make the protocol callback conditional or not, let me know if that needs to be changed.

[monich]

looks reasonable from the first glance, please give me a few days, I promise to take a closer look!

[mlehtima]

Also added missing implementation for gbinder_writer_append_fds and updated the version info for that because it was never functional in the old version.

[monich]

I trust you that it actually works :)