Fix loading binary data from deleted files in GTK

The dialog keeps info about last operation. This patch checks that last
file exists before reading it (thanks, Crisis)

Author: sbaldovi

ChangeLog

@@ -10,6 +10,7 @@
            found (Alberto Garcia).
          * WidgetUI: rearrange AY register and Z80 flags in the debugger
            (Gergely Szasz).
+         * GTK UI: Fix loading binary data from deleted files (thanks, Crisis).
 
 2021-02-27  Philip Kendall  <philip-fuse@shadowmagic.org.uk>
 

ui/gtk/binary.c

@@ -200,7 +200,7 @@ menu_file_loadbinarydata( GtkAction *gtk_action GCC_UNUSED,
    * If the filename is blank it's not been selected previously.
    * Pop up the file selector.
    */
-  if( !load_info.filename )
+  if( !load_info.filename || !compat_file_exists( load_info.filename ) )
   {
     load_info.filename = ui_get_open_filename( "Fuse - Load Binary Data" );
     if( !load_info.filename )