The result of parsing qemu-options.def depends on whehter or not
MAP_POPULATE is defined, so make sure to include sys/mman.h before
including qemu-options.h.

Reported by Frank Arnold.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>