then
AC_CHECK_HEADERS(mach/mach_init.h mach/host_priv.h mach/mach_error.h mach/mach_host.h mach/mach_port.h mach/mach_types.h mach/message.h mach/processor_set.h mach/processor.h mach/processor_info.h mach/task.h mach/thread_act.h mach/vm_region.h mach/vm_map.h mach/vm_prot.h mach/vm_statistics.h mach/kern_return.h)
AC_CHECK_HEADERS(CoreFoundation/CoreFoundation.h IOKit/IOKitLib.h IOKit/IOTypes.h IOKit/ps/IOPSKeys.h IOKit/IOBSD.h IOKit/storage/IOBlockStorageDriver.h)
then
AC_CHECK_HEADERS(mach/mach_init.h mach/host_priv.h mach/mach_error.h mach/mach_host.h mach/mach_port.h mach/mach_types.h mach/message.h mach/processor_set.h mach/processor.h mach/processor_info.h mach/task.h mach/thread_act.h mach/vm_region.h mach/vm_map.h mach/vm_prot.h mach/vm_statistics.h mach/kern_return.h)
AC_CHECK_HEADERS(CoreFoundation/CoreFoundation.h IOKit/IOKitLib.h IOKit/IOTypes.h IOKit/ps/IOPSKeys.h IOKit/IOBSD.h IOKit/storage/IOBlockStorageDriver.h)