[leaks-runner] Get more accurate results by subtracting two differing iteration counts.
[leaks-runner] Get more accurate results by subtracting two differing iteration counts.

Previously, we had some white listing lists for allocations that were assigned
into globals during a benchmarks running. Now we instead run two different
iterations with the second running an additional time. Then we subtract the
counts.

This enables me to get rid of the whitelist.

khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift