auxiliary: support for transfers using staging resources

auxiliary: support for transfers using staging resources

Direct3D 10/11 has no concept of transfers. Applications instead
create resources with a STAGING or DYNAMIC usage, copy between them
and the real resource and use Map to map the STAGING/DYNAMIC resource.

This util module allows to implement Gallium drivers as a Direct3D
driver would be implemented: transfers allocate a resource with
PIPE_USAGE_STAGING, and copy the data between it and the real resource
with resource_copy_region.