- normalise some tab/space issues.
- fix (debugger-only useful) struct srmmu_pte::pg_pfnum to be the
  right size.
- add SRMMU_TEPTERBO as a PTE type -- supersparc-II only feature
  of mapping pages in reverse-byte-order (eg little endian by
  default, but there's also a global RBO flag, that makes this
  flag big-endian.)  we don't use it (yet?)

(mrg)