[PATCHv7 0/4] kexec-tools: add support for Xen 4.4

[David Vrabel <david.vrabel@citrix.com>]

The series adds support for the new hypercall ABI which should be
provided by Xen 4.4.  Images are loaded into Xen directly with no
kernel involvement.

Please do not apply until the hypervisor side patches are applied to
Xen.

Patch 1 makes libxc 4.4 mandatory for Xen support.

Patch 2-3 remove uses of /proc/iomem in favour of libxc.

Patch 4 adds the support for loading, unloading, and exec'ing an image
in Xen.

This series explicitly drops support for older version of libxc/Xen as
supporting kexec on these hypervisors requires kernel support that
will never be available upstream.

Changes in v7:
- extend extra segment to 0-1 MiB so the VGA memory is accesible by
  the image.

Changes in v6:
- Close libxc handle a few error paths.

Changes in v5:
- Dropped the purgatory patch.

Changes in v4:
- KEXEC_ARCH_DEFAULT => EM_386
- add segment in the crash case for the backup src.

Changes in v3 (not posted):
- Rebased

Changes in v2:
- Patch from Don Sultz: use libxc for vmcoreinfo.
- Use xc_get_max_cpus() to get number of PCPUs.
- Enable unload and exec of images.

David