Also add a length parameter to wtap_optionblock_set_option_string
Change-Id: I8c7bbc48aa96b5c2a91ab9a17980928d6894f1ee
Reviewed-on: https://code.wireshark.org/review/15505
Reviewed-by: Anthony Coddington <anthony.coddington@endace.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>