session.h: Support ifindex greater than 255

Change ifindex of struct session_t to int to support kernel environments
where ifindex can be over 255.

Change-Id: I03e42a237533424515f58fc30f9ac50282c11712
Signed-off-by: Jon Shallow <supjps-libcoap@jpshallow.com>
Signed-off-by: Olaf Bergmann <bergmann@tzi.org>
1 file changed