Rename qemu-options.h to qemu-options.def

Rename qemu-options.h to qemu-options.def as it is not a header file
for general use and this leaves space for a proper qemu-options.h

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Acked-by: Juan Quintela <quintela@redhat.com>
Acked-by: Richard Henderson <rth@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>