Commit parts of SF patch #462759

Use #define X509_NAME_MAXLEN for server/issuer length on an SSL
object.

Update doc strings for socket.ssl() and ssl methods read() and
write().

PySSL_SSLwrite(): Check return value and raise exception on error.
Use int for len instead of size_t.  (All the function the size_t obj
was passed to our from expected an int!)

PySSL_SSLread(): Check return value of PyArg_ParseTuple()!  More
robust checks of return values from SSL_read().