Nuke yet more obvious #include duplications.

ok deraadt@
Document behavior of atexit() when called in a DSO that is later unloaded.
Would be nice to document when/where this originated (in glibc?) if
anyone knows...

tweaks by schwarze@
ok jmc@ espie@ kettenis@ schwarze@ dimitry(at)google.com
split crypt_checkpass off into a new file
Oops, make sure camellia is compiled on platforms without an arch-specific
Makefile.inc (i.e. landisk and m88k)
change prototype for crypt_newhash. the login_cap_t is a holdover from its
pwd_gensalt origins, but a string argument works equally work and is more
friendly to consumers beyond local user accounts.
ok deraadt
Let crypt_checkpass() set EACCES after bcrypt_checkpass() failure;
ok tedu@
add ERRORS, HISTORY, AUTHORS, Copyright year, and some missing macros;
ok tedu@ on a previous version
space needed between macro args and punctuation;
MPE support, begone.  ok tedu
Fix incorrect escape.
mop up a barely started project... getting in the way of grepping the tree!
Mention the -no_tls1_[12] options
check crypt() for null. noticed by Jonas Termansen
introduce a hashspace define and check that there's enough space to
write out a hash. also simplify writing out the hash.
push some global data down into functions to make this threadlier.
only doing what's needed for crypt_hashpass. sigh.
revert the bludgeoning of DES. if we need a thread safe crypt, maybe it's
better to find one instead of continuing to mangle this mess.
no need for md5 xr
rand48(3) not drand48(3) to align with the actual man page and Xr
entries.
Warn people to use arc4random() in DESCRIPTION so they see it using
the same text from random.3.
Don't describe random() as "better".
Remove the bug about rand() being faster.
Add a bug about historical implementations seeding very poorly.