client.c: Modified error exit when calling a server method

Now the client checks to see if the GSOAP error is the network device bind,
exiting with it (value 50) or exiting with 2 otherwise.

Signed-off-by: Erik Alexandre Pucci <eap08@c3sl.ufpr.br>
Acked-by: Ricardo Tavares de Oliveira <rto07@c3sl.ufpr.br>
Signed-off-by: Danilo K. S. Yorinori <danilok@c3sl.ufpr.br>