[gthumb] meson: error if libbrasero not available

[Paolo Bacchilega <paobac src gnome org>]

commit 1f9d28d7f5300c2bb5e77a7b551cfba2386fdc0d
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Mon Oct 23 19:21:21 2017 +0200

    meson: error if libbrasero not available

 extensions/meson.build |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/extensions/meson.build b/extensions/meson.build
index ac75a10..28cde03 100644
--- a/extensions/meson.build
+++ b/extensions/meson.build
@@ -33,7 +33,9 @@ subdir('photo_importer')
   
 # exporters
 subdir('export_tools')
-subdir('burn_disc')
+if use_libbrasero
+  subdir('burn_disc')
+endif
 subdir('contact_sheet')
 if with_webservices
   subdir('oauth')