[gnote] Fix potential crash on exit

[Aurimas Černius <aurimasc src gnome org>]

commit ec23c0da59eaf6779726bd98f7889fc87917994c
Author: Aurimas Černius <aurisc4 gmail com>
Date:   Sun Dec 21 23:45:11 2014 +0200

    Fix potential crash on exit

 src/gnote.cpp |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/src/gnote.cpp b/src/gnote.cpp
index d6322c5..b78eedb 100644
--- a/src/gnote.cpp
+++ b/src/gnote.cpp
@@ -77,7 +77,9 @@ namespace gnote {
 
   Gnote::~Gnote()
   {
-    delete m_prefsdlg;
+    if (m_prefsdlg) {
+      delete m_prefsdlg;
+    }
     delete m_manager;
 #ifdef HAVE_X11_SUPPORT
     delete m_keybinder;