- Introduce some macros for field names, so that endpt, pendpt,

  - Introduce some macros for field names, so that endpt, pendpt,
    addr and taddr don't have to be defined any more, so that <sys/mman.h>
    can be included for proper prototypes of munmap() and friends.
  - rename our GETPID to MINIX_GETPID to avoid a name conflict with
    other sources
  - PM needs its own munmap() and munmap_text() to avoid sending messages
    to VM at the startup phase. It *does* want to do that, but only
    after initialising. So they're called again with unmap_ok set to 1
    later.
  - getnuid(), getngid() implementation