Change lsearch()'s "base" argument to require a non-const pointer to
align with POSIX and other systems.

Pointed out by Elliott Hughes on tech
ok deraadt
zap trailing whitespace;
Remove "const" from the lsearch(3) manual's synopsis too.

Reminded by Rafael Neves
missing newline
Cleanup portable arc4random fork detection code:

1. Use "len" parameter instead of sizeof(*rs).

2. Simplify the atfork handler to be strictly async signal safe by
simply writing to a global volatile sig_atomic_t object, and then
checking for this in _rs_forkdetect().  (Idea from discussions with
Szabolcs Nagy and Rich Felker.)

3. Use memset(rs, 0, sizeof(*rs)) to match OpenBSD's MAP_INHERIT_ZERO
fork semantics to avoid any skew in behavior across platforms.

ok deraadt
Change _rs_allocate so it can combine the two regions (rs and rsx)
into one if a system has an awesome getentropy().  In that case it
is valid to totally throw away the rsx state in the child.  If the
getentropy() is not very good and has a lazy reseed operation, this
combining is a bad idea, and the reseed should probably continue to
use the "something old, something new" mix.  _rs_allocate() can
accomodate either method, but not on the fly.
ok matthew
Fix strtonum range to unbreak -pass fd:0

ok deraadt@
fixup typos