Cleanup a few compile warnings in latest snapshot:

extensions/libipt_dscp_helper.c:69: warning: 'dscp_to_name' defined but not used
extensions/libipt_sctp.c: In function 'print_chunks':
extensions/libipt_sctp.c:465: warning: value computed is not used
extensions/libipt_sctp.c:477: warning: value computed is not used

Resolves bug #457.

Phil