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

[Uwe Scholz <uwescholz src gnome org>]

commit aa5353335d388a51217443419eaa6f08aa8cb19d
Author: Andreas Henriksson <andreas fatal se>
Date:   Tue Apr 18 23:41:38 2017 +0200

    fix warning: ISO C++ forbids converting a string constant to 'char*'
    
    viewer-widget.cc: In function ‘void gviewer_image_status_update(ImageRender*, ImageRender::Status*, 
GViewer*)’:
    viewer-widget.cc:232:29: error: ISO C++ forbids converting a string constant to ‘char*’ 
[-Werror=write-strings]
             char *size_string = ""; // size_string = gnome_vfs_format_file_size_for_display (bytes);
                                 ^~

 src/intviewer/viewer-widget.cc |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/intviewer/viewer-widget.cc b/src/intviewer/viewer-widget.cc
index f16638d..069daa0 100644
--- a/src/intviewer/viewer-widget.cc
+++ b/src/intviewer/viewer-widget.cc
@@ -229,7 +229,7 @@ static void gviewer_image_status_update(ImageRender *obj, ImageRender::Status *s
     if (status->image_width > 0 && status->image_height > 0)
     {
         gchar zoom[10];
-        char *size_string = ""; // size_string = gnome_vfs_format_file_size_for_display (bytes);
+        char *size_string = strdup(""); // size_string = gnome_vfs_format_file_size_for_display (bytes);
 
         if (!status->best_fit)
             g_snprintf(zoom, sizeof(zoom), "%i%%", (int)(status->scale_factor*100.0));
@@ -242,6 +242,7 @@ static void gviewer_image_status_update(ImageRender *obj, ImageRender::Status *s
                     ngettext ("bit/sample", "bits/sample", status->bits_per_sample),
                     size_string,
                     status->best_fit?_("(fit to window)"):zoom);
+        free(size_string);
     }
 
     gtk_signal_emit (GTK_OBJECT (viewer), gviewer_signals[STATUS_LINE_CHANGED], temp);