Previously, VFIO functions were not compiled in and exported if
VFIO compilation was disabled. Fix this by actually compiling
all of the functions unconditionally, and provide missing
prototypes on Linux.
Fixes: 279b581c897d ("vfio: expose functions")
Fixes: 73a639085938 ("vfio: allow to map other memory regions")
Fixes: 964b2f3bfb07 ("vfio: export some internal functions")
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
6e8a721044