[PATCH 00 of 16] libxl: autogenerate type definitions and destructor functions

[Ian Campbell <ian.campbell@citrix.com>]

The series introduces auto-generation of the type definitions used in
the libxl interface followed by auto-generation of a destructor
function for each type. In the future it may be possible to use the
related data structures for other purposes, for example auto-generation
of the functions to marshal between C and language binding data types.

tools/_libxl_types.h should be identical both before applying and
after applying+building "libxl: autogenerate _libxl_types.h" apart
from a "DO NOT EDIT" header.

Since last time:
* rebase, many precurors were committed

Since the time before that:
* rebased
* corrected Makefile dependencies to include libxltypes.idl
* manually implemented libxl_file_reference_destroy since it is more
  complex than just freeing the contained types.
* Made libxl_file_reference_{map,unmap} into internal functions.
* Added typedefs for various types:
  - libxl_cpumap
  - libxl_hwcap
* Made libxl_xen_console_reader an opaque type and by making the definition
  internal.
* moved more types from libxl.h to _libxl_types.h. I think all those
  which it makes sense to generate are now accounted for.
* disabled destructor generation for types which have no interesting
  fields (i.e. had empty destructor functions). I have retained the
  empty destructors for types which belong to a set where some types
  do have a valid need for a destructor funntion (e.g. libxl_device_*
  or libxl_*info)
* Audit for usages of libxl_device_* and libxl_*info which can use the
  new destructors. I'm sure I haven't caught them all.

Tested with:
       create
       destroy (w/ valgrind)
       block-list (w/ valgrind)
       network-list (w/ valgrind)
       network-attach (w/ valgrind)
       network-detach (w/ valgrind)
       vcpu-list (w/ valgrind)
       cd-insert (w/ valgrind)

create, other than dry run, and valgrind don't currently play
nice together. It's not clear if its all the foreign mappings or something
else. I've tested creating both HVM and PV guests.

Ian.