Fix duplicated `ConfiguredComponent`s
We generated them both the old way (only internal libs) and the new way
(arbitrary sublibraries), leading to this:
$ cabal new-configure my-package -v
[...]
Component graph for my-package-0.2.0.0: component exe:my-exe
component my-package-0.2.0.0-inplace-my-exe
include base-4.11.1.0
include base-4.11.1.0
include word8-0.1.3-968d6922e82a4ae480d10bc205e047a27af7804ae8fb577c4b6eeb868f99ee3b
include word8-0.1.3-968d6922e82a4ae480d10bc205e047a27af7804ae8fb577c4b6eeb868f99ee3b
[...]
...which didn't have any effect on the build except for some duplicate
output, but could lead to problems in the future.
Now we only generate them the new way.