Remove FLAG_INTERACTIVE test from "login as:" prompt. Kelly John Carney

pointed out that Plink would attempt to use a zero-length username iff
a remote command was specified (because the FLAG_INTERACTIVE test was
erroneously combined with the no-username test).

I don't think this will break non-interactive use; in the cases which
behave differently, Plink would be attempting to use the empty
username, which was almost certainly wrong, whereas now it will give a
prompt (which can be avoided with -batch as usual).

(Although perhaps we should attempt to use a local username as a guess for
the remote username, as PSCP does? I've not done this.)

[originally from svn r4831]

ssh.c

@@ -2757,7 +2757,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     fflush(stdout);
     {
-	if ((flags & FLAG_INTERACTIVE) && !*ssh->cfg.username) {
+	if (!*ssh->cfg.username) {
 	    if (ssh_get_line && !ssh_getline_pw_only) {
 		if (!ssh_get_line("login as: ",
 				  s->username, sizeof(s->username), FALSE)) {
@@ -4841,7 +4841,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	     * with change_username turned off we don't try to get
 	     * it again.
 	     */
-	} else if ((flags & FLAG_INTERACTIVE) && !*ssh->cfg.username) {
+	} else if (!*ssh->cfg.username) {
 	    if (ssh_get_line && !ssh_getline_pw_only) {
 		if (!ssh_get_line("login as: ",
 				  s->username, sizeof(s->username), FALSE)) {