[gnome-builder] flatpak: use meson for gtksourceview

[Christian Hergert <chergert src gnome org>]

commit 11d07454b6183310ff29b2e596abeab33deda5d0
Author: Christian Hergert <chergert redhat com>
Date:   Sat Apr 20 20:42:00 2019 -0700

    flatpak: use meson for gtksourceview

 build-aux/flatpak/org.gnome.Builder.json | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/build-aux/flatpak/org.gnome.Builder.json b/build-aux/flatpak/org.gnome.Builder.json
index 363c926b8..3fc01584f 100644
--- a/build-aux/flatpak/org.gnome.Builder.json
+++ b/build-aux/flatpak/org.gnome.Builder.json
@@ -249,6 +249,7 @@
         },
         {
             "name" : "gtksourceview",
+            "buildsystem" : "meson",
             "sources" : [
                 {
                     "type" : "git",