opengl: Add support for rendering on bitmaps

[Tomas Carnecky]

Huw D M Davies wrote:
>         Huw Davies <huw at codeweavers.com>
>         Add support for rendering on bitmaps


This patch breaks World of Warcraft, reverting this patch makes WoW work 
again. This is the error:

X Error of failed request:  BadMatch (invalid parameter attributes)
   Major opcode of failed request:  142 (GLX)
   Minor opcode of failed request:  13 (X_GLXCreateGLXPixmap)
   Serial number of failed request:  410
   Current serial number in output stream:  411

tom