don't export operative roundabouts twice

Created by: das-g

Operative roundabouts are exported twice into layer road_l. See e.g. way 4768697 in <staging host>/media/osmaxx/outputfiles/f1c9a18e-470d-42a3-ba81-a4e0e9fbf8e8/2016-06-09-KreisverkehrHolzh%C3%A4usern-f1c9a18e-470d-42a3-ba81-a4e0e9fbf8e8.spatialite.zip

osm_id	lastchange	geomtype	aggtype	type	name	label	tags	ref	oneway	z_order	bridge	tunnel
4768697		W	major_road	primary			lit"=>"yes", "source:maxspeed"=>"CH:urban	4;368	no	7	0	0
4768780		W	major_road	primary			source:maxspeed"=>"CH:urban", "destination:forward"=>"Sins;Hünenberg	368	no	7	0	0
23492119		W	major_road	primary	Luzernerstrasse	Luzernerstrasse	lit"=>"yes", "sidewalk"=>"both", "source:maxspeed"=>"CH:urban", "sidewalk:left:bicycle"=>"yes	4	no	7	0	0
33709836		W	major_road	primary	Holzhäusernstrasse	Holzhäusernstrasse	source:maxspeed"=>"CH:urban	368	no	7	0	0
42749088		W	major_road	primary	Chamerstrasse	Chamerstrasse	lit"=>"yes", "sidewalk"=>"both", "source:maxspeed"=>"CH:urban", "destination:forward"=>"Luzern;Rotkreuz", "destination:symbol:forward"=>"motorway	4	no	7	0	0
144073668		W	no_large_vehicle	footway					no	0	0	0
4768697		W	roundabout	primary			lit"=>"yes", "source:maxspeed"=>"CH:urban	4;368	no	7	0	0

This can be tested by running tests/inside_worker_test/nonop_way_test.py after including key-value pair TagCombination(highway='secondary', junction='roundabout'): 'secondary', in CORRESPONDING_OSMAXX_WAY_TYPES_FOR_OSM_TAG_COMBINATIONS there.

Interestingly enough, non-operative non-roundabouts aren't duplicated between road_l and nonop_l, because of a second mistake due to SQL's trinary logic: NULL NOT IN ('some', 'array') is NULL rather than TRUE and FALSE OR NULL is NULL (which is falsy). See e.g. <staging host>/media/osmaxx/outputfiles/39f21a8a-c2e5-4bc1-ab87-f9526848f85a/2016-06-09-StadttunnelZugS%C3%BCd-geplant-planned-39f21a8a-c2e5-4bc1-ab87-f9526848f85a.spatialite.zip