Bootstrap failure on MIPS

[Mark Mitchell]

Richard --

  The mips-sgi-irix6.5 bootstrap is failing now.  It's crashing
building cpphash.c with the stage1 cc1.  Somehow, mode of hard
register 2 is becoming `144' which is yielding severe confusion.

  It's then getting stuck in an endless loop in mark_regs_live_at_end
which is why I think you might be able to figure this out quicker than
I.  :-)

--
Mark Mitchell                   mark@codesourcery.com
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