[gtksourceview] build: set NO_AT_BRIDGE=1 in tests

[Christian Hergert <chergert src gnome org>]

commit 2b2e4ec6099b168319e18c0848917684a0c46f6d
Author: Christian Hergert <chergert redhat com>
Date:   Mon Sep 9 17:15:51 2019 -0700

    build: set NO_AT_BRIDGE=1 in tests
    
    On various beta systems for GNOME 3.34, we might not have access to the
    at-bridge. This fixes the test system to work without it, which isn't
    really something we want to be specifically testing anyway.

 testsuite/meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/testsuite/meson.build b/testsuite/meson.build
index 5405d9b7..f842a07a 100644
--- a/testsuite/meson.build
+++ b/testsuite/meson.build
@@ -4,6 +4,7 @@ test_env = [
   'G_DEBUG=gc-friendly',
   'GSETTINGS_BACKEND=memory',
   'MALLOC_CHECK_=2',
+  'NO_AT_BRIDGE=1',
 ]
 
 testsuite_c_args = [