socketoption sctp_add_streams returns -1 if both instrms and outstrms are 0

[hoelscher]

If an Application calls the setsockopt syscall with SCTP_ADD_STREAMS option to add 0 new incoming and 0 new outgoing streams, the syscall returns an error. The RFC doen't make any constraint for that values unless the limit of max streams. So that means that this would be a valid call.
Besides that both values 0 could be a legal combination without any effect.
see https://github.com/nplab/RFC6525_Testsuite/blob/master/api_tests/sctp-sr-api-as/sctp-sr-api-as-v-5-1.pkt