Remove get_cipher from SSL_METHOD.

Remove get_cipher from SSL_METHOD.

Inline the get_cipher implementation (including the special handling
for DTLS) in ssl_cipher_collect_ciphers() (the only consumer), remove
the get_cipher member of SSL_METHOD and mop up dtls1_get_cipher().

ssl3_get_cipher() has always had a strange property of being a reverse
index, which is relied on by the cipher list ordering code, since it
currently assumes that high cipher suite values are preferable. Rather
than complicating ssl3_get_cipher() (and regress), change the iteration
order in ssl_cipher_collect_ciphers() to match what it requires. Lastly,
rename ssl3_get_cipher() to be more descriptive.

ok tb@