revsetbenchmark: add more example for roots usages We test the `roots` revset in setting similar to our test for `heads`. Note that the algorithm used for roots can give result without consuming the full input set. This provides a significant speedup when testing or accessing a single value. We can't just replace it with simple, full algorithm like we did for `heads`. See performance number below: 0) roots((tip~100::) - (tip~100::tip)) 1) roots((0::) - (0::tip)) 2) roots(tip~100:) 3) roots(:42) 4) roots(not public()) 5) roots((0:tip)::) 6) roots(0::tip) 7) 42:68 and roots(42:tip) 8) roots(0:tip) 9) roots((:42) + (tip~42:)) 10) roots(all()) 11) roots(-10000:-1) 12) (-5000:-1000) and roots(-10000:-1) 13) roots(matching(tip, "author")) 14) roots(matching(tip, "author")) and -10000:-1 15) (-10000:-1) and roots(matching(tip, "author")) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 00) 0.000789 0.000801 0.000801 0.000819 0.000784 0.000774 0.000793 0.000816 0.000815 0.000831 0.000799 01) 0.097610 0.002717 0.096706 0.002615 0.059189 0.089033 0.059862 0.002644 0.098058 0.002640 0.058992 02) 0.000709 0.000117 0.000382 0.000136 0.000384 0.000724 0.000412 0.000133 0.000733 0.000159 0.000416 03) 0.000075 0.000064 0.000093 0.000080 0.000097 0.000089 0.000123 0.000079 0.000105 0.000102 0.000126 04) 0.000055 0.000071 0.000070 0.000087 0.000075 0.000066 0.000100 0.000085 0.000082 0.000110 0.000102 05) 0.088043 0.001084 0.087816 0.001097 0.048049 0.072454 0.047673 0.001089 0.088491 0.001163 0.047824 06) 0.058761 0.001727 0.059324 0.001850 0.058562 0.059198 0.058998 0.001743 0.058556 0.001874 0.059420 07) 0.000131 0.000121 0.000145 0.000138 0.000150 0.000142 0.000178 0.000135 0.000160 0.000163 0.000179 08) 0.058003 0.000077 0.032327 0.000093 0.031966 0.056812 0.031753 0.000092 0.057113 0.000116 0.031933 09) 0.000503 0.000145 0.000469 0.000161 0.000476 0.000564 0.000502 0.000160 0.000537 0.000187 0.000500 10) 0.056654 0.000058 0.033104 0.000073 0.032157 0.056598 0.031877 0.000071 0.056433 0.000094 0.031819 11) 0.005842 0.000081 0.001907 0.000101 0.001883 0.005868 0.001915 0.000099 0.005836 0.000122 0.001896 12) 0.003237 0.000634 0.001784 0.000655 0.001803 0.003245 0.001837 0.000649 0.003231 0.000680 0.001858