Update md5.h / md5.c from upstream OpenBSD

[DimitriPapadopoulos]

Changes are minimal, as upstream itself changed bzero() → memset().

Note that the new bzero_explicit() function call in upstream has been changed to a memset() function call, in the absence of a widely available memset_explicit() function for now.

Also update the URL of the OpenBSD source repository.

[DimitriPapadopoulos]

That's where upstream introduced a bzero_explicit() call, which we keep translating into a memset() call.

[alandekok]

Are there any functionality changes here? I'm not sure why these changes are needed.

[DimitriPapadopoulos]

No functionality changes. The rationale is that upstream have changed bzero() to memset() in their latest version 1.4. The header claims that the following changes have been applied to upstream version 1.1:

 *	with the following changes:
 *	#includes commented out.
 *	Support context->count as uint32_t[2] instead of uint64_t
 *	u_int* to uint*

That would be true compared to the latest upstream version 1.4, but not compared to upstream version 1.1, where the following comment would be required:

 *	change all occurrences of bzero() to memset()

I find it better to update the base upstream version from 1.1 to the latest 1.4, since it includes changes that have also been applied here, than documenting these changes in the header.

Here is the diff between upstream 1.1 and 1.4:
https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/crypto/md5.c.diff?r1=1.1&r2=1.4&f=h

This PR also fixes the URL of the OpenBSD source repository.

Finally, I wanted to point out that the explicit_bzero() call from upstream 1.4 has been transformed into a mere memset(). Perhaps I should add this to the changes listed in the comments, shouldn't I?

[DimitriPapadopoulos]

It just occurred to me that I should also update md5.h from 1.1 to 1.3, for consistency:

https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/crypto/md5.h.diff?r1=1.1&r2=1.3&f=h