[PATCH v5 00/19] libxl: improvements, prep for subprocess handling

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

This is the initial portion of my child process series which has been
acked and which I intend to apply right away.  Changes are exactly
those discussed on the list since v4; I'm reposting the final version
for form's sake.

Bugfixes for problems reported by Roger Pau Monne:
 02/19 libxl: ao: allow immediate completion
 03/19 libxl: fix hang due to libxl__initiate_device_remove
 04/19 libxl: Fix eventloop_iteration over-locking
 05/19 libxl: remove poller from list in libxl__poller_get

Other general bugfixes:
 01/19 .gitignore: Add a missing file
 06/19 libxl: Fix leak of ctx->lock
 07/19 tools: Correct PTHREAD options in config/StdGNU.mk
 08/19 libxl: Use PTHREAD_CFLAGS, LDFLAGS, LIBS
 09/19 tools: Use PTHREAD_CFLAGS, _LDFLAGS, _LIBS

Clarifications and improvements related to memory allocation:
 10/19 libxl: Crash (more sensibly) on malloc failure
 11/19 libxl: Make libxl__zalloc et al tolerate a NULL gc

Preparatory work for child process handling:
 12/19 libxl: Introduce some convenience macros
 13/19 libxl: include <ctype.h> and introduce CTYPE helper macro
 14/19 libxl: Provide libxl_string_list_length
 15/19 libxl: include <_libxl_paths.h> in libxl_internal.h
 16/19 libxl: abolish libxl_ctx_postfork

Event-related infrastructure and fixes:
 17/19 libxl: libxl_event.c:beforepoll_internal, REQUIRE_FDS
 18/19 libxl: Protect fds with CLOEXEC even with forking threads
 19/19 libxl: provide STATE_AO_GC

The remaining patches (20-31 from v4) remain outstanding.