gallium: add PIPE_CAP_MAX_WINDOW_RECTANGLES to all drivers

This says how many window rectangles are supported by the
implementation, although it may not exceed PIPE_MAX_WINDOW_RECTANGLES.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Brian Paul <brianp@vmware.com>
17 files changed