sys/param.h and move the MI numbers out of here. Also move the MI
defines. Also remove a couple defines not in use (not sure if it is
age, or OpenBSD origins for thse). Note the current values that are
overrides that appear to be odd in some way.
More cleanup could be done here: NBPG appears to be spelled PAGE_SIZE
these days. There's new ways to spell PGOFSET and PGSHIFT too, I
think. These constants duplicate the MI constants and are sprinkled
into the mips code only. Further investigation is needed.
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