[PATCH 0 of 6] xl PCI passthrough updates v3

[Gianni Tedesco <gianni.tedesco@citrix.com>]

my current libxl PCI-passthrough patch-queue rebased modulo what has alread 
been applied.

Changes since v1:
 1. Move pci FLR function in to libxl_pci.c - got it all in now.
 2. Properly initialize pci device structs in new code
 3. Incorporate suggestions from Stefano wrt. API and putting sysfs paths in
    macros.
 4. Rename libxl_device_pci_list to libxl_device_pci_list_assigned due to
    change in parameters for consistency with the rest of libxl PCI API.
 5. Also introduced a patch to centralise parsing of PCI BDF's and allow
    omission of the PCI domain as a short-hand for both config files and
    hot-plug command parameters. This also fixes an infinite loop in xl create
    if there is a parse error in the pci config.

Changes since v2:
 1. Use SYS_PCI_DEV macro in libxl_device_pci_reset
 2. Fix error in libxl_device_pci_list_assigned() as pointed out by Ian
    Campbell
 3. Get rid of scan_sys_pcidir() and implement inside
    libxl_device_pci_list_assignable() since we're not supporting pcistub
    driver now
 4. New patch: prevent attempting removal of non-attached device
 5. New patch: implement pci attach to explicitly defined virtual PCI slot
 6. New patch: corresponding to qemu-dm patch, detect pci insertion errors
    which are otherwise undetectable and cause a hang
 7. New patch: implement PCI passthrough for multi-function