make: fix bootstrap for native libraries

Restore (but in a hopefully better way) a step that installs native
libraries before trying a full `raco setup`, since the libraries
may be needed for the setup proces --- especially on Windows.
make: fix for PKGS=""
raco setup: try harder to delete files such as DLLs

If "sqlite3.dll" is installed as a foreign library but shouldn't
be, then `raco setup` cannot simply deleet the file, because
starting `raco setup` opened the DLL. To avoid that problem,
rename the file to start with "raco-setup-delete-", then attempt to
delete the renamed file; the delete won't work, but the file
will be moved out of the way, and a future `raco setup` can
clean up.

The prefix "raco-setup-delete-" thus becomes special on Windows for
the directories that hold foreign libraries, shared files, and
man pages, because `raco setup` will try to delete any file
that starts with "raco-setup-delete-".

It's all very ugly, but I don't have a better idea for the
problems that I keep hitting.