[vte] widget: Avoid unnecessary invalidations at hyperlinks

[Egmont Koblinger <egmontkob src gnome org>]

commit bca1cd274c1ffafea98f5b9e586b9069a781a318
Author: Egmont Koblinger <egmont gmail com>
Date:   Wed Sep 12 13:04:28 2018 +0200

    widget: Avoid unnecessary invalidations at hyperlinks
    
    https://gitlab.gnome.org/GNOME/vte/issues/44

 src/vte.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/vte.cc b/src/vte.cc
index cdd0a0d3..3055d622 100644
--- a/src/vte.cc
+++ b/src/vte.cc
@@ -5536,7 +5536,8 @@ Terminal::hyperlink_hilite_update()
 
         /* Underlining hyperlinks has precedence over regex matches. So when the hovered hyperlink changes,
          * the regex match might need to become or stop being underlined. */
-        invalidate_match_span();
+        if (m_match != nullptr)
+                invalidate_match_span();
 
         apply_mouse_cursor();