Remove duplicated code in EVP.

Second phase of EVP cipher overhaul.

Change functions like EVP_EncryptUpdate() so they now return a
value. These normally have software only implementations
which cannot fail so this was acceptable. However ciphers
can be implemented in hardware and these could return errors.

Beginnings of EVP cipher overhaul. This should eventually
enhance and tidy up the EVP interface.

This patch adds initial support for variable length ciphers
and changes S/MIME code to use this.

Some other library functions need modifying to support use
of modified cipher parameters.

Also need to change all the cipher functions that should
return error codes, but currenly don't.

And of course it needs extensive testing...

(meaning pointer to char) to des_cblock * (meaning pointer to
array with 8 char elements), which allows the compiler to
do more typechecking.  (The changed argument types were of type
des_cblock * back in SSLeay, and a lot of ugly casts were
used then to turn them into pointers to elements; but it can be
done without those casts.)

Introduce new type const_des_cblock -- before, the pointers rather
than the elements pointed to were declared const, and for
some reason gcc did not complain about this (but some other
compilers did).

functions transposed.

Submitted by:
Reviewed by:
PR: