self-concurrency effects on HighwaySystem::mileage_by_region

[yakra]

Does any single route have more mileage than its HighwaySystem::mileage_by_region?

[yakra]

RailwayData @ eeea42fb2e1178e0d8f7f6e5ef631385ba46a8ab

#include "tasks/threaded/CompStats.cpp"

cout << "system | route | mileage | system<br>region<br>mileage | ratio | system<br>mileage | ratio | region<br>active<br>preview | ratio\n";
cout << "| - | - | - | - | - | - | - | - | - |\n";
for (auto& h : HighwaySystem::syslist)
  for (auto& r : h.routes)
  {	double hmbr = h.mileage_by_region.at(r.region);
	double r_ratio = 100 * r.mileage / hmbr;
  	if (r_ratio > 100.0000000000001)
	{	double s_mi = h.total_mileage();
		double r_mi = r.region->active_preview_mileage;
		printf("%s | %s | %.2f | %.2f | %.2f%% | %.2f | %.2f%% | %.2f | %.2f%%\n",
			&h.systemname[0], &r.root[0],
			r.mileage, hmbr, r_ratio,
			s_mi, 100*r.mileage/s_mi,
			r_mi, 100*r.mileage/r_mi);
	}
  }
return 0;

system	route	mileage	system region mileage	ratio	system mileage	ratio	region active preview	ratio
chncrh	chntj.hsrjinghu	65.44	64.03	102.20%	3688.60	1.77%	64.03	102.20%
espave	espvc.gijvin	160.24	159.89	100.22%	1567.46	10.22%	531.83	30.13%
gbnht	eng.ecmlhul	216.50	216.04	100.21%	216.04	100.21%	7502.19	2.89%
gbngw	wls.swalml	102.22	101.21	101.01%	1125.58	9.08%	781.73	13.08%
usaamtk	fl.ss	533.63	506.40	105.38%	21421.67	2.49%	797.68	66.90%
usarrm	ar.blueln	2.90	2.35	123.63%	2.35	123.63%	312.89	0.93%
usast	az.sunlink	4.06	3.86	105.22%	3.86	105.22%	821.30	0.49%
usaelpsc	tx.elpasostr	5.00	4.89	102.24%	4.89	102.24%	1755.63	0.28%
usagal	tx.galisltro	4.24	3.20	132.46%	3.20	132.46%	1755.63	0.24%
usamck	tx.mlntro	4.55	3.76	120.81%	3.76	120.81%	1755.63	0.26%

[yakra]

zzz.list: PA I-376 69A 69B

3,4c3,4
< Overall in active systems: 0.49 of 1240604.32 mi (0.00%)
< Overall in active+preview systems: 0.49 of 1909958.47 mi (0.00%)
---
> Overall in active systems: 0.66 of 1240608.15 mi (0.00%)
> Overall in active+preview systems: 0.66 of 1909962.89 mi (0.00%)
6c6
< PA: 0.49 of 17661.58 mi (0.00%), 0.49 of 17661.58 mi (0.00%)
---
> PA: 0.66 of 17661.74 mi (0.00%), 0.66 of 17661.74 mi (0.00%)
127c127
< System usausb (active) overall: 0.49 of 7544.54 mi (0.01%)
---
> System usausb (active) overall: 0.99 of 7545.04 mi (0.01%)
164c164
<   PA: 0.49 of 289.53 mi (0.17%)
---
>   PA: 0.99 of 290.02 mi (0.34%)

The bug:
Active, a/p, and overall stats get double-credited only 1/3 of the time,
from the 2 usausb routes but not the 1 interstate or the 3 usaus routes.
End result is 1.33x credit, 0.66 mi instead of 0.99 mi as intended.

Changes to compute_stats.cpp:

• It should be obvious where this goes:

  unsigned int rte_concurrency_count = 1; // own route

• At the end of the 1st switch's default block:

  if (other->route == r)
    rte_concurrency_count++;

• In the 2nd switch, multiply every fractional += by rte_concurrency_count.