When porting XTS-related code from OpenBSD I forgot to update copyright (only
OpenBSD was credited in one of two commits). Fix it.

Reported by:	Theo de Raadt <deraadt@cvs.openbsd.org>
Reviewed by:	Damien Miller <djm@mindrot.org>
Use the fact that the AES-NI instructions can be pipelined to improve
performance... Use SSE2 instructions for calculating the XTS tweek
factor...  Let the compiler do more work and handle register allocation
by using intrinsics, now only the key schedule is in assembly...

Replace .byte hard coded instructions w/ the proper instructions now
that both clang and gcc support them...

On my machine, pulling the code to userland I saw performance go from
~150MB/sec to 2GB/sec in XTS mode.  GELI on GNOP saw a more modest
increase of about 3x due to other system overhead (geom and
opencrypto)...

These changes allow almost full disk io rate w/ geli...

Reviewed by:	-current, -security
Thanks to:	Mike Hamburg for the XTS tweek algorithm

Conflicts:
	sys/conf/files.amd64
make it so that from/to can be missaligned as it can happen (the geli
regression manages to do it)...  We use a packed struct to coerce
gcc/clang into producing unaligned loads (there is not packed pointer
attribute, otherwise this would be easier)...

use _storeu_ and _loadu_ when using the structure is overkill...

be better at using types properly...  Since we allocate our own key
schedule and make sure it's aligned, use the __m128i type in various
arguments to functions...

clang ignores __aligned on prototypes and gcc errors on them, leave them
in comments to document that these function arguments are require to be
aligned...

about all that changes is movdqa -> movdqu from reading the diff of the
disassembly output...

Noticed by:	symbolics at gmx.com
MFC after:	3 days
fix broken style(9) in r258399

Pointed out by:	brd