Only initialize/cleanup libpciaccess once
Only initialize/cleanup libpciaccess once

libpciaccess has many bugs in its pci_system_init/cleanup
functions that makes calling them multiple times unwise.
eg it will double close() FDs, and leak other FDs.

* src/node_device/node_device_udev.c: Only initialize
  libpciaccess once
(cherry picked from commit 2215050edd8adefbf0ff21c5cbf09685877492d6)

Signed-off-by: Steve Hodgson <eb20a6615749cf04ff61aa37e18f749ed6d01446@solarflare.com>

sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-