- Update Xen patches to 3.7-rc3 and c/s 1202.
    - extend base interfaces to support multi-page rings for
      frontend/backend communication.
    - blkback: allow using multiple page frontend communication ring.
    - blkfront: allow using multiple page backend communication ring.
    - ACPI: Store valid ACPI tables passed via early initrd in
      reserved memblock areas.
    - ACPI: Fix build when disabled.
    - ACPI: Cleanup acpi_initrd_override declaration and remove
      ifdefs.
    - config.conf: Re-enable Xen configs.
    - Update x86 config files.
    - Delete patches.xen/xen3-acpi_override_2_2.patch.