svga: add context pointer to the invalidate surface interface

svga: add context pointer to the invalidate surface interface

With this patch, we will specify the current context
when we invalidate the surface before the surface is
put back to the recycled surface pool. This allows the
winsys layer to use the specified context to do the
invalidation rather than using the last context that
referenced the surface. This prevents race condition if
the last referenced context is now made current in another thread.

Tested with MTT glretrace, NobelClinicianViewer.

Reviewed-by: Sinclair Yeh <syeh@vmware.com>