[mutter] meson: Add 'plain' test setup

[Marge Bot <marge-bot src gnome org>]

commit b1c8ce110c1128a4c5032036f522d7fc5e65500a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Oct 28 14:55:41 2021 +0200

    meson: Add 'plain' test setup
    
    This is useful if one wants to run 'meson test' inside
    meta-dbus-runner.py. Doing so makes it possible to run e.g. 'meson test
    --gdb'.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2093>

 meson.build | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/meson.build b/meson.build
index 3b0ad40911..2eea6ac1e6 100644
--- a/meson.build
+++ b/meson.build
@@ -303,6 +303,8 @@ if have_tests
     exe_wrapper: default_test_wrappers,
   )
 
+  add_test_setup('plain')
+
   add_test_setup('CI',
     env: [
       'MUTTER_DEBUG_DUMMY_MODE_SPECS=800x600@10.0',