Introduce full coverage tests for module routerset.c.

src/common/container.c

src/common/container.h

src/or/geoip.c

src/or/geoip.h

src/or/nodelist.c

src/or/nodelist.h

src/or/policies.c

src/or/policies.h

src/or/routerparse.c

src/or/routerparse.h

src/or/routerset.c

src/or/routerset.h

src/test/include.am

src/test/test.c

src/test/test_routerset.c