ktest: Fix make_min_config to handle new assign_configs call

Commit 6071c22e1755 "ktest: Rewrite the config-bisect to actually work"
fixed the config-bisect to work nicely but in doing so it broke
make_min_config by changing the way assign_configs works.

The assign_configs function now adds the config to the hash even if
it is disabled, but changes the hash value to be that of the
line "# CONFIG_FOO is not set". Unfortunately, the make_min_config
test only checks to see if the config is removed. It now needs to
check if the config is in the hash and not set to be disabled.

Cc: stable@vger.kernel.org # 3.17+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tools/testing/ktest/ktest.pl

@@ -3571,7 +3571,9 @@ sub test_this_config {
     undef %configs;
     assign_configs \%configs, $output_config;
 
-    return $config if (!defined($configs{$config}));
+    if (!defined($configs{$config}) || $configs{$config} =~ /^#/) {
+	return $config;
+    }
 
     doprint "disabling config $config did not change .config\n";