Avoid out of boundary access when checking invalid long filenames.

Addressed by NetBSD in revision 1.24, but instead of ignoring the filename,
consider it invalid -- because it is.

ok krw@, tedu@
Add MAP_ANONYMOUS as a synonym for MAP_ANON, per POSIX proposal

ok miod
Now that sd(4) drives under softraid0 have their cache flushed when
DVACT_POWERDOWN is propagated in this subtree, there is no need for
this shutdown hook anymore. RIP.

ok kettenis@
Backport support for -Wframe-larger-than=N to base GCC

This is the flag name that modern GCC and Clang have de facto
standardized on for the functionality that we locally named
-Wstack-larger-than-N.

ok brad, miod
No need to talk about config_activate(), we don't have it anymore.
Kill a blatantly outdated (and now wrong) comment
Put boot signature always at end of 512 byte sector, even on disks with
larger sector sizes.  512 bytes is also the smallest valid sector size.

Merged from NetBSD's revision 1.24.

ok krw@, tedu@
Add mallocarray(9)

While here, change malloc(9)'s size argument from "unsigned long" to
"size_t".

ok tedu
Oops, fix man page typo.

thx Jean-Philippe Ouellet
To make sure that at least anything is tested, add a length check
per default for the default length value in check_logs().  If a
test doesn't want this check, it has to disable it explicitly with
nocheck.  Also remove unneeded nocheck switches for deeper testing.
KNF.
Print "%s (removed)" into relayd log and test for that string.
suggested by reyk@
Nuke OPENSSL_NONPIC_relocated since nothing uses it.

ok miod@
Not initializing "next free cluster" is better than pointing at a cluster
that is in use.

Merged from NetBSD rev 1.9.

ok krw@ (who came up with the same diff)
Uninitialized values (-1) in FSInfo are perfectly valid.

Merged from NetBSD revision 1.24.

ok krw@ (who came up with the same diff)
boot(9): Remove comments about RB_*, "cold", and savectx()

Again remove slightly different comments to reduce diffs.  These will be
re-added once boot() become MI and its specification is clearly re-defined.

OK miod@
add additional includes required to build with -DOPENSSL_NO_DEPRECATED
ok eric@ gilles@
Make sure SRP_Calc_client_key() returns NULL instead of a pristine BN_new()
upon error; from Florian Zumbiehl (florz , florz . de) on tech@
Make sure srp_Calc_k() digest operations are checked for error; from
Florian Zumbiehl (florz , florz . de) on tech@