[telegnome] Fix build with vala 0.36

[Colin Watson <cjwatson src gnome org>]

commit ecb6f70980d3673b133702694eb6d1ff7bb11b13
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Sat Jun 17 23:33:07 2017 -0400

    Fix build with vala 0.36

 src/prefs.vala |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/prefs.vala b/src/prefs.vala
index 2605efe..49b4ef8 100644
--- a/src/prefs.vala
+++ b/src/prefs.vala
@@ -240,7 +240,11 @@ public class Prefs : Object {
                Channel channel;
                channel_store.get (iter, Column.CHANNEL, out channel, -1);
                string old_uuid = channel.uuid;
+#if VALA_0_36
+               channel_store.remove (ref iter);
+#else
                channel_store.remove (iter);
+#endif
                sync_channel_children ();
 
                /* Clear out settings debris from the deleted channel if