[vte] widget: Fix a memory leak in set_colors

[Egmont Koblinger <egmontkob src gnome org>]

commit be0ae73fe58b9a3b37a0ca9568ac5999416552a2
Author: Egmont Koblinger <egmont gmail com>
Date:   Sun Jul 24 19:06:52 2016 +0200

    widget: Fix a memory leak in set_colors
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768994

 src/vtegtk.cc |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/vtegtk.cc b/src/vtegtk.cc
index 5ecec5e..944ab1c 100644
--- a/src/vtegtk.cc
+++ b/src/vtegtk.cc
@@ -2897,6 +2897,7 @@ vte_terminal_set_colors(VteTerminal *terminal,
                          background ? &bg : nullptr,
                          pal, palette_size);
         impl->set_background_alpha(background ? background->alpha : 1.0);
+        g_free(pal);
 }
 
 /**