Fix compilation of userland stack.
Fix compilation of userland stack.

This fixes #246.

faithfracture/usrsctp,sctplab/usrsctp,CoolmanCZ/usrsctp,weinrank/usrsctp,CoolmanCZ/usrsctp,sctplab/usrsctp,CoolmanCZ/usrsctp,CoolmanCZ/usrsctp,sctplab/usrsctp,faithfracture/usrsctp,faithfracture/usrsctp,weinrank/usrsctp,weinrank/usrsctp