Report host/port in connect exception message

[yaitskov]

Hi,

I propose to append target address to exception message in connect function.
Haskell doesn't have stack trace support as good as java.
It is really hard to figure out where a problem is if an application connects to many places,
because an exception message doesn't have target domain/ip address and port.

connectLoop :: SocketAddress sa => Socket -> Ptr sa -> CInt -> IO ()
connectLoop s p_sa sz = withFdSocket s $ \fd -> loop fd
  where
    errLoc = "Network.Socket.connect: " ++ show s

[kazu-yamamoto]

Could you implement it by yourself and send us a PR?

[yaitskov]

#529