proc: Export the max_protection bitmap of map entries

[kib]

sys/kern/kern_proc.c

2605

etc

sys/sys/user.h

572

Did you considered packing maxprotection into kve_protection with PROT_MAX() instead, to not consume spare?

[markj]

sys/sys/user.h

572

I hadn't considered that. I'm not convinced that it's really important to avoid consuming spares, given how many we have left, but I will change it.

[markj]

I forgot that I posted this. Superseded by commit 409c2fa385aa34baf7dd86bed2e86fbff16ad86d.