Upstream: Should be
Reason: Fixes compilation with -fno-common

diff --git a/src/splitpoints_window.h b/src/splitpoints_window.h
index 36738ac..d727a7d 100644
--- a/src/splitpoints_window.h
+++ b/src/splitpoints_window.h
@@ -59,7 +59,7 @@ enum {
   COL_TRACK = 13,
   COL_COMMENT = 14,
   NUM_COLUMNS = 15
-} tree_columns;
+} extern tree_columns;
 
 gchar *get_splitpoint_name(gint index, ui_state *ui);
 gint get_first_splitpoint_selected(gui_state *gui);