Enable GLX_SGI_make_current_read for radeon.

Enable GLX_SGI_make_current_read for radeon.

Added code to track the drawable bound to the context for reading.  In
addition, when a drawable is initially bound (for reading or drawing)
or when the size of the drawable changes, update the size of the
framebuffer object that back the drawable (for software fallbacks).

Deprecate the old GetBufferSize interface.

Bump the driver date.

These changes were tested with wincopy on both direct rendering and
accelerated indirect rendering (AIGLX).