[smuxi/stable] Engine-IRC: fix build

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

commit 7536131a0904104e6758e57b63175be6475ceb0a
Author: Mirco Bauer <meebey meebey net>
Date:   Wed Dec 16 17:49:54 2015 +0100

    Engine-IRC: fix build
    
    This fixes a build regression introduced in
    d7c7508ce478b7074957a8aac8f779bf3d4f7d10

 src/Engine-IRC/Protocols/Irc/IrcProtocolManager.cs |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/Engine-IRC/Protocols/Irc/IrcProtocolManager.cs 
b/src/Engine-IRC/Protocols/Irc/IrcProtocolManager.cs
index 0f08193..14934ba 100644
--- a/src/Engine-IRC/Protocols/Irc/IrcProtocolManager.cs
+++ b/src/Engine-IRC/Protocols/Irc/IrcProtocolManager.cs
@@ -21,6 +21,7 @@
  */
 
 using System;
+using System.IO;
 using System.Text;
 using System.Text.RegularExpressions;
 using System.Security.Cryptography.X509Certificates;