On the revision:

- Make the .def file a prerequisite of the libs type target and only for
  Windows.

- Canonicalize the license in the package manifest.

- Normalize C comments in the tests source code:

  Replace

  /*
   * ...
   */

  with

  /* ...
   */

On the release:

- Use legal{} target type for legal documentation (LICENSE, AUTHORS, etc).

  Note that this requires bumping build2 version requirement to 0.13.0.