NAN value

I have modified the current tree so it will compile on BSD/OS, and
probably FreeBSD.

I don't have a NAN define. My libm source looks like it assigns
HUGE_VAL to those entries requiring a NAN.

I have also commented out the inclusion of "nan.h" because I don't have
that either.

This will probably require further tweaking for other OS's.

-- 
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