tests: fix modules-test 'duplicate test case' error

./configure --enable-sdl --audio-drv-list=sdl --enable-modules

Will generate two identical test names: /$arch/module/load/sdl
Which generates an error like:

(tests/modules-test:23814): GLib-ERROR **: 18:23:06.359: duplicate test case path: /aarch64//module/load/sdl

Add the subsystem prefix in the name as well, so instead we get:

/$arch/module/load/audio-sdl
/$arch/module/load/ui-sdl

Signed-off-by: Cole Robinson <crobinso@redhat.com>
Message-Id: <d64c9aa098cc6e5c0b638438c4959eddfa7e24e2.1573679311.git.crobinso@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit eca3a94)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

tests/modules-test.c

@@ -64,7 +64,8 @@ int main(int argc, char *argv[])
     g_test_init(&argc, &argv, NULL);
 
     for (i = 0; i < G_N_ELEMENTS(modules); i += 2) {
-        char *testname = g_strdup_printf("/module/load/%s", modules[i + 1]);
+        char *testname = g_strdup_printf("/module/load/%s%s",
+                                         modules[i], modules[i + 1]);
         qtest_add_data_func(testname, modules + i, test_modules_load);
         g_free(testname);
     }