random() was switched in https://reviews.freebsd.org/rS364219     to return result of new prng32().

Since then, random() no longer behaves as documented returning
number with 32 bit range instead of 31 bit range, and
is inconsistent with previous/current doc and usage.

That breaks the computation of things like the "prob xx" match field
in ipfw rules in tests like the one at:
 https://cgit.freebsd.org/src/tree/sys/netpfil/ipfw/ip_fw2.c#n2475
(designed to assume the documented 31 bit range for random()).

Other non-exhaustive examples of places that break because of that changes are:
   sys/dev/bce/if_bcereg.h
   sys/kern/subr_stats.c
   sys/netinet/cc/cc_cdg.c

Over the more than 30 years that random() has been documented as
having a 31 bit range, there seems to be a few places that have
hardcoded assumptions that max value is 0x7fffffff, so the only
safe choice is trying to purge random() use or restore it to
is previous bounds rather than trying to adjust all existing
code to a new bound.