Return an error when sending a a buffer with NULL.
Return an error when sending a a buffer with NULL.

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