Handle the case where the previous PDU has left an extra CRLF in the stream.RFC 2626   In the interest of robustness, servers SHOULD ignore any empty   line(s) received where a Request-Line is expected. In other words, if   the server is reading the protocol stream at the beginning of a   message and receives a CRLF first, it should ignore the CRLF.

Change-Id: I97ba94f451463c8facd2c20bf6b7364f095119e7
Reviewed-on: https://code.wireshark.org/review/2808
Reviewed-by: Anders Broman <a.broman58@gmail.com>