Don't return 1 if not ran as super_user, like the other tests.

testsuite/expect/test15.4

@@ -46,7 +46,7 @@ if {[test_front_end] != 0} {
 	exit $exit_code
 } elseif {[test_super_user] == 0} {
 	send_user "\nWARNING: This test must be done from a super-user\n"
-	exit 1
+	exit 0
 }
 
 #

testsuite/expect/test28.6

@@ -47,7 +47,7 @@ if {[get_array_config] < [expr $array_size + 1]} {
 	exit 0
 } elseif {[test_super_user] == 0} {
 	send_user "\nWARNING: This test must be done from a super-user\n"
-	exit 1
+	exit 0
 }
 
 make_bash_script $script "