Important SSL 2.0 bugfixes (bugs found while implementing msg_callback).

reveal whether illegal block cipher padding was found or a MAC
verification error occured.

In ssl/s2_pkt.c, verify that the purported number of padding bytes is in
the legal range.

missed any.

This compiles and runs on Linux, and external applications have no
problems with it.  The definite test will be to build this on VMS.

as a shared library without RSA.  Use #ifndef NO_SSL2 instead of
NO_RSA in ssl/s2*.c.

Submitted by: Kris Kennaway <kris@hub.freebsd.org>
Modified by Ulf Möller

SSL_MODE_ENABLE_PARTIAL_WRITE, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER.

Submitted by:
Reviewed by:
PR: