[gnome-commander/ConvertWarningsToErrors] fix warning: ISO C++ forbids converting a string constant to 'gchar *'

[Uwe Scholz <uwescholz src gnome org>]

commit 7dc53f6b172bcb1559eccc1ddd5dd61e463cf000
Author: Andreas Henriksson <andreas fatal se>
Date:   Tue Apr 18 23:29:42 2017 +0200

    fix warning: ISO C++ forbids converting a string constant to 'gchar *'
    
    eggcellrendererkeys.cc: In function ‘gchar* egg_accelerator_get_label(guint, GdkModifierType)’:
    eggcellrendererkeys.cc:259:23: error: ISO C++ forbids converting a string constant to ‘gchar* {aka 
char*}’ [-Werror=write-strings]
             keyval_name = "";
                           ^~

 src/eggcellrendererkeys.cc |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/eggcellrendererkeys.cc b/src/eggcellrendererkeys.cc
index 4913cf9..840f2bc 100644
--- a/src/eggcellrendererkeys.cc
+++ b/src/eggcellrendererkeys.cc
@@ -254,7 +254,7 @@ gchar *egg_accelerator_get_label (guint accel_key, GdkModifierType accel_mods)
     static const gchar text_hyper[] = "Hyper+";
 #endif
 
-    gchar *keyval_name = gdk_keyval_name (gdk_keyval_to_upper (accel_key));
+    const gchar *keyval_name = gdk_keyval_name (gdk_keyval_to_upper (accel_key));
     if (!keyval_name)
         keyval_name = "";