SocketImpl: fix success path by setting NoError

Initialize the error to SocketError::NoError in case of success.

Otherwise, the error wasn't initialized in the success path for the
socket poller, and it was reaching an unknown error because of that.

src/Nazara/Network/Posix/SocketImpl.cpp

@@ -395,6 +395,9 @@ namespace Nz
 			return 0;
 		}
 
+		if (error)
+			*error = SocketError::NoError;
+
 		return static_cast<unsigned int>(result);
 	}