[gnome-clocks] Update gsound build system to meson

[Bilal Elmoussaoui <bilelmoussaoui src gnome org>]

commit 3383ca65e5a13fbc06b76aae58293893645cc6b6
Author: Caio Carrara <eu caiocarrara com br>
Date:   Tue Aug 3 19:49:32 2021 -0300

    Update gsound build system to meson
    
    Recently gsound was updated to use meson build system[1], so this change
    updates it on gnome-clock side.
    
    [1] - https://gitlab.gnome.org/GNOME/gsound/-/merge_requests/6

 build-aux/flatpak/org.gnome.clocks.json | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/build-aux/flatpak/org.gnome.clocks.json b/build-aux/flatpak/org.gnome.clocks.json
index 1bf5e841..60d880eb 100644
--- a/build-aux/flatpak/org.gnome.clocks.json
+++ b/build-aux/flatpak/org.gnome.clocks.json
@@ -66,6 +66,7 @@
         },
         {
             "name": "gsound",
+            "buildsystem": "meson",
             "sources": [
                 {
                     "type": "git",