[smuxi] Common: made thread of SingleApplicationInstance a background thread

[Mirco M. M. Bauer <mmmbauer src gnome org>]

commit 34ec120f396d89a2764e52f88084538d1d172b6f
Author: Mirco Bauer <meebey meebey net>
Date:   Thu Apr 23 06:48:35 2015 +0200

    Common: made thread of SingleApplicationInstance a background thread
    
    The Unix signal handler thread should not prevent the application from
    terminating.

 src/Common/SingleApplicationInstance.cs |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/Common/SingleApplicationInstance.cs b/src/Common/SingleApplicationInstance.cs
index ed9831e..31ff338 100644
--- a/src/Common/SingleApplicationInstance.cs
+++ b/src/Common/SingleApplicationInstance.cs
@@ -202,6 +202,7 @@ namespace Smuxi.Common
                     UnixSignal.WaitAny(shutdown_signals);
                     ReleaseFileLock();
                 });
+                UnixSignalThread.IsBackground = true;
                 UnixSignalThread.Start();
             }
         }