[PATCH v7 00/24] libxl: subprocess handling

[Ian Jackson <ian.jackson@eu.citrix.com>]

This has now been tested and appears to work for me.

Changes since v6 are bugfixes, comments from the list addressed, and
three new patches (marked with "*" below).

   01/24 libxl: handle POLLERR, POLLHUP, POLLNVAL properly
   02/24 libxl: support multiple libxl__ev_fds for the same fd
   03/24 libxl: event API: new facilities for waiting for subprocesses
 * 04/24 autoconf: trim the configure script; use autoheader
   05/24 autoconf: New test for openpty et al.
   06/24 libxl: provide libxl__remove_file et al.
   07/24 libxl: Introduce libxl__sendmsg_fds and libxl__recvmsg_fds
   08/24 libxl: Clean up setdefault in do_domain_create
   09/24 libxl: provide libxl__datacopier_*
   10/24 libxl: provide libxl__openpty_*
   11/24 libxl: ao: Convert libxl_run_bootloader
   12/24 libxl: make libxl_create_logfile const-correct
   13/24 libxl: log bootloader output
   14/24 libxl: Allow AO_GC and EGC_GC even if not used
   15/24 libxl: remove ctx->waitpid_instead
   16/24 libxl: change some structures to unit arrays
   17/24 libxl: ao: convert libxl__spawn_*
   18/24 libxl: make libxl_create run bootloader via callback
   19/24 libxl: provide progress reporting for long-running operations
   20/24 libxl: remove malloc failure handling from NEW_EVENT
   21/24 libxl: convert console callback to libxl_asyncprogress_how
 * 22/24 libxl: clarify definition of "slow" operation
 * 23/24 libxl: child processes cleanups
 * 24/24 libxl: aborting bootloader invocation when domain dies