MINOR: stream-int: Notify caller when an error is reported after a rcv_pipe()

MINOR: stream-int: Notify caller when an error is reported after a rcv_pipe()

In si_cs_send(), when an error is found on the CS or the connection at the
beginning of the function, we return 1 to notify the caller some processing may
be triggered. So, it seems logical to do the same after the call to rcv_pipe().

This patch is not flagged as a bug because no strange behaviour was yet observed
without it. It is just a proactive fix to be consistent.