MPX ABI extension

[Kalle Olavi Niemitalo]

Ilya Enkovich <enkovich.gnu@gmail.com> writes:

>  - When we pass (return) pointer on register, we use the next
> available bound register to pass (return) bounds

>From the wording, it seems function pointers get bounds too.
If so, it might be good to state that explicitly.
I suppose they would be all-of-memory bounds though,
due to the lack of hardware support for checking them.