Define the vm_ooffset_t and vm_pindex_t types as machine-independend.
The types are for the byte offset and page index in vm object. They
are similar to off_t, which is defined as 64bit MI integer. Using MI
definitions will allow to provide consistent MD values of vm
object-related maximum sizes.
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
MFC after: 1 week