Find commit where exhaustivity V became slower.

[nicolasstucki]

Run benchmarks for exhaustivity V between 2207 and 2225.

[liufengyun]

The tests are still running, the numbers we got so far points to scala/scala3#2197:

tests/exhaustivity-V.scala, 2206, Mon Apr 10 10:30:18 2017 +0200, 80f9b6d, 1539.247, Wed Aug  2 01:30:10 CEST 2017, 5928.500 2764.294 2125.282 1992.031 1825.874 1815.940 1804.638 1764.344 1709.072 1602.605 , 1727.830 1570.156 1562.542 1572.068 1563.342 1621.671 1604.223 1790.256 1549.574 1542.556 1535.938 1531.982 1520.495 1535.005 1528.114 1519.587 1521.185 1518.139 1530.913 1525.583
tests/exhaustivity-V.scala, 2197, Mon Apr 10 10:33:32 2017 +0200, 318700f, 2300.6205, Wed Aug  2 01:34:02 CEST 2017, 6935.061 3328.739 2874.619 2840.029 2771.814 2744.011 2669.833 2620.002 2471.407 2335.814 , 2351.880 2356.177 2313.637 2301.890 2294.475 2299.544 2291.117 2299.636 2300.647 2303.761 2320.406 2300.594 2424.915 2322.111 2279.552 2267.236 2274.625 2279.598 2311.667 2279.097

[liufengyun]

This is now done and deployed. I'll check if there's room to improve the performance.