* src/libxl/libxl_driver.c, src/lxc/lxc_driver.c,
  src/qemu/qemu_driver.c, src/remote/remote_driver.c,
  src/test/test_driver.c, src/uml/uml_driver.c,
  src/vbox/vbox_tmpl.c, src/xen/xen_driver.c: Convert
  to threadsafe APIs