Doing away with NGROUPS_MAX in src/sys/sys/syslimits.h?

[Boris Kochergin]

Ahoy. I got bitten by this today--a system I administer for someone had 
users in more than 16 groups, so I had to bump the value, recompile the 
kernel, and reboot. It seems desirable to (at the very least) make this 
a read-only tunable that can be set using /boot/loader.conf, so as to 
avoid source modification and kernel recompilation. I had a look around, 
and noticed that NGROUPS_MAX is used to construct static arrays in a 
couple of locations ("ibcs2_gid_t iset[NGROUPS_MAX];"). It seems that 
malloc(9)/MALLOC(9) can be used to allocate memory for the array 
instead, and panic() (or something) can be called if the allocation 
fails, no? Is that about the gist of it? If I'm not overlooking 
something major, I'd like to take a stab at it.

-Boris