stop asking users to report unexpected GP login argument arg[19]="4"

We still don't know what this one means (my wild guess is that it's telling the client to prefer IPv4), but newer GP servers always send it and it's basically uninteresting.

Signed-off-by: Daniel Lenski <dlenski@gmail.com>

auth-globalprotect.c

@@ -299,7 +299,7 @@ static const struct gp_login_arg gp_login_args[] = {
 	{ .opt="portal-userauthcookie", .show=1},
 	{ .opt="portal-prelogonuserauthcookie", .show=1},
 	{ .unknown=1 },
-	{ .unknown=1 },				        /* have seen value of "4" in some logs */
+	{ .opt="usually-equals-4", .show=1 },           /* newer servers send "4" here, meaning unknown */
 };
 static const int gp_login_nargs = (sizeof(gp_login_args)/sizeof(*gp_login_args));