Some timers on certain device and test combinations can produce noisy
results, affecting the reliability of performance measurements. One
notable example of this is the Canaan K230 RISC-V development board.

An option to adjust the number of samples by an exponent (--runs) has
been added, allowing developers to increase the sample count for more
reliable results.
Signed-off-by: J. Dekker <jdek@itanimul.li>