Import SHA-3 code into libc and libkern.

No new public symbols in libc, but publishing the symbols is a simple
matter if/when we decide to do so.

Proposed on tech-kern and tech-userlevel with no objections:

https://mail-index.NetBSD.org/tech-kern/2017/11/11/msg022581.html
https://mail-index.NetBSD.org/tech-userlevel/2017/11/11/msg010968.html

new hmac function.

Add MurmurHash2 -- a non-cryptographic hash function by Austin Appleby.
The code is taken from the upstream and is in the public domain.

OK christos@

branches: 1.11.42;
As discussed back in June, remove hmac_sha1 and hmac_md5 from libc, to
reduce bloat and namespace trouble. (both were never public; hmac_sha1
is moved to libcrypt now because it is used locally there)

Put public domain MD2 implementation in libc/hash/md2.

Organize hashing in libc.

Compile SHA2 again.

Not running lint on kernel code fooled me into thinking this was safe.
Don't compile SHA2 code until I resolve warnings.

Add SHA2 hashing routines to userland.

At the moment there's only code for the init/transform/update/final
routines.

Man-page from OpenBSD.

branches: 1.5.2;
Add support for SHA1 hashed passwords.
The algorithm used is essentially PBKDF1 from RFC 2898 but using
hmac_sha1 rather than SHA1 directly (suggested by smb@research.att.com).

* The format of the encrypted password is:
* $<tag>$<iterations>$<salt>$<digest>
*
* where:
* <tag> is "sha1"
* <iterations> is an unsigned int identifying how many rounds
* have been applied to <digest>. The number
* should vary slightly for each password to make
* it harder to generate a dictionary of
* pre-computed hashes. See crypt_sha1_iterations.
* <salt> up to 64 bytes of random data, 8 bytes is
* currently considered more than enough.
* <digest> the hashed password.

hmac.c implementes HMAC as defined in RFC 2104 and includes a unit
test for both hmac_sha1 and hmac_sha1 using a selection of the Known
Answer Tests from RFC 2202.

It is worth noting that to be FIPS compliant the hmac key (password)
should be 10-20 chars.

fix typo: rmd160l.c -> rmd160hl.c

Pull in RIPEMD-160 functions from OpenBSD - this has the same API as our MD4,
MD5 and SHA1 stuff.

use ${ARCHDIR} instead of ${.CURDIR}/arch/${MACHINE_ARCH} where appropriate
libc builds on pmax again

add sha1 functions, like md5/4