[gnome-builder] build: specify target glib version when invoking valac

[Christian Hergert <chergert src gnome org>]

commit 9d3a9f2ebfa104c060665eb9edc3a591af9e84a6
Author: Christian Hergert <chergert redhat com>
Date:   Thu Jun 8 13:37:37 2017 -0700

    build: specify target glib version when invoking valac
    
    We already target a most-recent GLib, so we can specify this to Vala too
    so that we get modern-style generated GObject-based C.
    
    This also happens to work around this vala bug:
    
      https://bugzilla.gnome.org/show_bug.cgi?id=783543

 plugins/vala-pack/meson.build |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plugins/vala-pack/meson.build b/plugins/vala-pack/meson.build
index 17c9fc7..f6d9576 100644
--- a/plugins/vala-pack/meson.build
+++ b/plugins/vala-pack/meson.build
@@ -76,6 +76,7 @@ shared_module('vala-pack-plugin', vala_pack_sources,
     libide_vapi,
   ],
   vala_args: [
+    '--target-glib=2.52',
     '--pkg=posix',
     '--pkg=libdazzle-1.0',
     '--pkg=libpeas-1.0',