Improve compilation if INET or INET6 is not defined.
Improve compilation if INET or INET6 is not defined.

xwhuang/sctp-refimpl,sctplab/sctp-refimpl,sctplab/sctp-refimpl,xwhuang/sctp-refimpl,deepak899/sctp-refimpl,deepak899/sctp-refimpl,sctplab/sctp-refimpl,sctplab/sctp-refimpl,deepak899/sctp-refimpl,xwhuang/sctp-refimpl,xwhuang/sctp-refimpl,deepak899/sctp-refimpl,sctplab/sctp-refimpl,xwhuang/sctp-refimpl,sctplab/sctp-refimpl,deepak899/sctp-refimpl,deepak899/sctp-refimpl,xwhuang/sctp-refimpl