Arrange to call net_pending_errors on Unix, which we've never actually

remembered to do before! Also some related fixes, such as that after
we do so we should immediately stop selecting on the socket in
question.

[originally from svn r9363]

unix/uxpterm.c

@@ -17,6 +17,16 @@ Backend *select_backend(Conf *conf)
     return &pty_backend;
 }
 
+void net_pending_errors(void)
+{
+    /*
+     * Stub version of net_pending_errors(), because gtkwin.c has to
+     * be prepared to call it when linked into PuTTY and therefore we
+     * have to avoid a link failure when linking gtkwin.c in turn into
+     * a non-networked application.
+     */
+}
+
 int cfgbox(Conf *conf)
 {
     /*