Fix OSNetworkSystem.acceptImpl error handling; additional clean-up.

The main reason for this patch is that acceptImpl was checking the wrong
return code.

I've also removed the BADSOCKET and UNKNOWNSOCKET errors because they were
being used interchangeably with the BADDESC error and weren't genuinely
meaningful.

I've also removed the bogus checks for 0 as a file descriptor, which is
perfectly valid (if unlikely).

I've factored this common snippet out.
1 file changed