Fix color of files with no extension.

Based on all other references, unknown_file.color is a color, not an
index into custom_colors[]. Previously, custom_colors[-1] was returned
for files without an extension, accessing outside array boundaries
and making files without an extension black, which is hard to see.

Change-Id: Ia0883aba929582324b767df7828a36a84c0b36b9

apps/filetypes.c

@@ -514,7 +514,7 @@ int filetype_get_color(const char * name, int attr)
         return custom_colors[0];
     extension = strrchr(name, '.');
     if (!extension)
-        return custom_colors[unknown_file.color];
+        return unknown_file.color;
     extension++;
 
     i = find_extension(extension);