Handle reassembly of handshake messages

Works only with GnuTLS for now, OpenSSL packs other records in the same
datagram after the last fragmented one, which we don't handle yet.

Also, ssl-opt.sh fails the tests with valgrind for now: we're so slow with
valgrind that gnutls-serv retransmits some messages, and we don't handle
duplicated messages yet.
3 files changed