This is required by the check-fast target because each test is slurped up into a submodule.
Since 3b6314c3 the pretty printer seems to only print trait bounds for `ast::ty_path(...)`s that have a generics arguments list. That seems wrong, so let's always print them. Closes #9253, un-xfails test for #7673.
3b6314c3
Closes #2074. Closes #5008. Closes #7519. Closes #7673. Closes #7770. Closes #8171.