openssl speed: add an '-unaligned n' option

openssl speed: add an '-unaligned n' option

All hashes and ciphers covered by speed should be able to handle unaligned
input and output. The buffers used in openssl speed are well aligned since
they are large, so will never exercise the more problematic unaligned case.

I wished something like this was available on various occasions. It would
have been useful to point more easily at OpenSSL's broken T4 assembly.
Yesterday there were two independent reasons for wanting it, so I sat down
and did it. It's trivial: make the allocations a bit larger and use buffers
starting at an offset inside these allocations. Despite the trivality, I
managed to have a stupid bug. Thanks miod.

discussed with jsing
ok miod