svga/winsys: Propagate surface shared information to the winsys

svga/winsys: Propagate surface shared information to the winsys

The linux winsys needs to know whether a surface is shared.
For guest-backed surfaces we need this information to avoid allocating a
mob out of the mob cache for shared surfaces, but instead allocate a shared
mob, that is never put in the mob cache, from the kernel.

Also previously, all surfaces were given the "shareable" attribute when
allocated from the kernel. This is too permissive for client-local surfaces.
Now that we have the needed info, only set the "shareable" attribute if the
client indicates that it needs to share the surface.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Cc: "10.1" <mesa-stable@lists.freedesktop.org>