Fixes from Christoph Egger

Fixes from Christoph Egger

- xen-vl-exra.c: Only compile pci_emulation_add() w/  CONFIG_PASSTHROUGH
- Fix compiler confusion with tokens after #endif
- qemu-common.h: Fix merge botch with upstream
- qemu-xen.h: remove redundant declaration of pci_xen_platform_init
- xen_platform.c: take declaration of pci_xen_platform_init from
  xen_platform.h
- xen_platform.c: Make platform_fixed_ioport_save and
  platform_fixed_ioport_load static. They have no prototypes and aren't
  used elsewhere

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>