embedded-tls does not understand message fragmenting

[bugadani]

This was mentioned in #75 (comment) but that issue has since been closed.

[lulf]

Does it need to for 99% of embedded use cases?

[bugadani]

No idea, but on one hand, it might help with MaxFragmentLength extension to tune things, and on the other, I just want this fact visible.

Edit: my guess here is that it's probably not necessary, but also that we might implement something for it under the alloc flag. There's no reason not to be compliant if there is a way to do so :) Definitely not something I'll spend time on any time soon, though.