libxc: use new (replacement) mmap-batch ioctl

libxc: use new (replacement) mmap-batch ioctl

Replace all calls to xc_map_foreign_batch() where the caller doesn't
look at the passed in array to check for errors by calls to
xc_map_foreign_pages(). Replace all remaining calls by such to the
newly introduced xc_map_foreign_bulk().

As a sideband modification (needed while writing the patch to ensure
they're unused) eliminate unused parameters to
uncanonicalize_pagetable() and xc_map_foreign_batch_single(). Also
unmap live_p2m_frame_list earlier in map_and_save_p2m_table(),
reducing the peak amount of virtual address space required.

All supported OSes other than Linux continue to use the old ioctl for
the time being.

Also change libxc's MAJOR to 4.0 to reflect the API change.

Signed-off-by: Jan Beulich <jbeulich@novell.com>