Add sem_wait timeout on the kconsumerd thread

Add sem_wait timeout on the kconsumerd thread

It's unlikely to happen but is the kconsumerd was not able to send us
the sock ready command, at least the session daemon will not stall
forever. A 30 seconds timeout is added and error is handle after that.

Also adds the handling of the sem_init ret value and adds mutex lock
around the kconsumerd pid in the same function.

There was also a problem on error code handling where LTTCOMM error was
returned by spawn kconsumerd function but handled as if it might be
negative at the end of the call chain. This was preventing to return the
right error code to the client when the kconsumerd failed.

Signed-off-by: David Goulet <david.goulet@polymtl.ca>