Change the REAL-to-INTEGER casting behavior so that if the REAL value

is greater than 9223372036854775807.0 then it is cast to the latest
possible integer, 9223372036854775807.  This is sensible and the way
most platforms work in hardware.  The former behavior was that oversize
REALs would be cast to the smallest possible integer, -9223372036854775808,
which is the way Intel hardware works.

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