fix mapgen special build errors

[LyleSY]

Summary

Bugfixes "fix mapgen special build errors"

Purpose of change

Fix build

Describe the solution

Removing existing road requirements from new map specials

Describe alternatives you've considered

Set the minimum occurrences of these non-unique map specials:

• wind turbine
• Motel
• motel-twd

...to zero as stated in the relevant doc. See https://github.com/CleverRaven/Cataclysm-DDA/blob/master/doc/OVERMAP.md

Add related terrains to overmap_terrain_coverage_whitelist

Testing

WIP

Additional context

Thanks to @Maleclypse for the idea

[Maleclypse]

Assuming this passes the test you'll want to update the summary notes.

[Procyonae]

Why are you removing the existing road requirement? These are supposed to place on preexisting roads to look more natural, it doesn't make sense to have a motel at the end of a long road to nowhere, they also have priority -1 to ensure they place after all the other roads are in

[LyleSY]

Why are you removing the existing road requirement? These are supposed to place on preexisting roads to look more natural, it doesn't make sense to have a motel at the end of a long road to nowhere, they also have priority -1 to ensure they place after all the other roads are in

It's a different idea that @Maleclypse had for the same issue. My personal concern is to get the mapgen to a place where it can reliably run. I don't have a strong opinion on this solution.

[Procyonae]

I don't really see why a 6 month old change needs a bandaid fix, I've just opened up a new world to check nothing derped recently and in 3 OMs there's 3 successful wind turbine spawns and 6 varying motel spawns, with at least 1 of each. Either the test fail wants changing so it doesn't just accumulate failed minimum occurrence attempts regardless of successful spawns in between resulting in it failing over large areas unless I've misremembered how it works or the special placement code wants improving to be more reliable. I also have no clue why you think this would speed up mapgen

[LyleSY]

Agreed, I don't think this solution will speed up mapgen. I've removed that

[LyleSY]

Closing for now. Happy to reopen if there is interest in the future.