Fix a bug in the handling of non-blocking SCTP 1-to-1 sockets. When using
this code in the userland stack, it could result in a loop. This happened on iOS.
However, I was not able to reproduce this when using the code in the kernel.
Thanks to Eugen-Andrei Gavriloaie for reporting the issue and proving detailed
information to find the root of the problem.

Approved by: re (gjb)
MFC after: 1 week