Operation Time

We measure the clock-time of the integer-addition operation.  We use
the addition operation as the unit of measurement for the other
arithmetic operations, so the clock-time of the other arithmetic
operations can be reconstructed from this value.

The database entries are:

cost_add.frequency.mhz
cost_add.time.ns

...where cost_add.fequency.mhz is the number of addition operations
that can execute per second (in megahertz, so multiply this value by
one million), and cost_add.time.ns is the measured number of
nanoseconds for a single addition operation.

The return type for both values is double.

