Ensure there are no duplicates in Elements.dependencies()
When we are not recursing, Element.dependencies()
uses a much more
light weight codepath since it just needs to print the direct
dependencies. However, this simple codepath was not accounting for
duplicates, in case something is both a build time and run time
dependency.
One way this manifested itself was in bst show --format %{deps}
, but
it would also affect anything that was using this method to iterate on
the dependencies.
Fixes #1308 (closed).