[smuxi/stable] Frontend-GNOME: fix NRE when not all encodings are available

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

commit 699f395263f65bd496a4ca88e2929c18d7521f9c
Author: Mirco Bauer <meebey meebey net>
Date:   Sun Nov 15 13:11:46 2015 +0100

    Frontend-GNOME: fix NRE when not all encodings are available
    
    On openSUSE with Mono 4.0.4.1 and not having the mono-locale-extras package
    installed leads to an NullReferenceException in PreferencesDialog._Load(). Thus
    added de-reference guards.

 .../Preferences/PreferencesDialog.cs               |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/Frontend-GNOME/Preferences/PreferencesDialog.cs 
b/src/Frontend-GNOME/Preferences/PreferencesDialog.cs
index 15a0406..6e7fed8 100644
--- a/src/Frontend-GNOME/Preferences/PreferencesDialog.cs
+++ b/src/Frontend-GNOME/Preferences/PreferencesDialog.cs
@@ -343,6 +343,9 @@ namespace Smuxi.Frontend.Gnome
             foreach (EncodingInfo encInfo in Encoding.GetEncodings()) {
                 try {
                     Encoding enc = Encoding.GetEncoding(encInfo.CodePage);
+                    if (enc == null || enc.EncodingName == null) {
+                        continue;
+                    }
                     string encodingName = enc.EncodingName.ToUpper();
 
                     if (!enc.IsSingleByte && enc != Encoding.UTF8) {