[PATCH 0/13] execute hotplug scripts from libxl

[Roger Pau Monne <roger.pau@citrix.com>]

This series have been splitted in several patches, to make them easier 
to review. Also the amount of changes introduced is quite important, 
since apart from all the hotplug necessary functions and 
modifications, libxl_domain_destroy has been converted to an async op. 
This was necessary in order to have async operations during device 
removal.

Also, as an important change, disk and nics are added at different 
points for HVM and device model based guests, since we need the disk 
in order to start Qemu, but the nic hotplug scripts should be called 
at a later point, when Qemu has created the corresponding tap device.

[PATCH 01/13] libxl: pass env vars to libxl__exec
[PATCH 02/13] libxl: fix libxl__xs_directory usage of transaction
[PATCH 03/13] libxl: add libxl__xs_path_cleanup
[PATCH 04/13] libxl: move libxl_device_disk_add to libxl_device
[PATCH 05/13] libxl: move libxl_device_nic_add to libxl_device
[PATCH 06/13] libxl: cleanup libxl__device_{disk,nic}_add
[PATCH 10/13] libxl: add option to choose who executes hotplug
[PATCH 11/13] libxl: set nic type to VIF by default

All the changes above are bug fixes, code motion or helper functions, 
that will be used by the other patches in the list.

[PATCH 07/13] libxl: convert libxl_domain_destroy to an AO op
[PATCH 08/13] libxl: convert libxl_device_disk_add to an async
[PATCH 09/13] libxl: convert libxl_device_nic_add to an async
[PATCH 12/13] libxl: call hotplug scripts for disk devices from
[PATCH 13/13] libxl: call hotplug scripts for nic devices from libxl

This patches contain the meat, specially 07/13. The other ones become 
quite trivial once 07/13 is applied.