improve pam_cleartext.test a bit

mysql-test/suite/plugins/r/pam_cleartext.result

@@ -5,6 +5,9 @@ grant proxy on pam_test to test_pam;
 show variables like 'pam%';
 Variable_name	Value
 pam_use_cleartext_plugin	ON
+#
+# same test as in pam.test now fails
+#
 drop user test_pam;
 drop user pam_test;
 uninstall plugin pam;

mysql-test/suite/plugins/t/pam_cleartext.test

@@ -3,10 +3,20 @@
 
 show variables like 'pam%';
 
+--write_file $MYSQLTEST_VARDIR/tmp/pam_good.txt
+not very secret challenge
+9225
+select user(), current_user(), database();
+EOF
+
+--echo #
+--echo # same test as in pam.test now fails
+--echo #
 --error 1
---exec echo FAIL | $MYSQL_TEST -u test_pam --plugin-dir=$plugindir
+--exec $MYSQL_TEST -u test_pam --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good.txt
+
+--remove_file $MYSQLTEST_VARDIR/tmp/pam_good.txt
 
 drop user test_pam;
 drop user pam_test;
 uninstall plugin pam;
-