sysutils/vmdktool: Set TEST_TARGET and WWW, and fix ALL_TARGET

[0mp]

Summary

sysutils/vmdktool: Set TEST_TARGET and WWW, and fix ALL_TARGET

- Set TEST_TARGET. We need a utility called prove that comes with Perl 5 so set
  USES=perl5 as well.
- Set ALL_TARGET to vmdktool. The default one, all, attempts to build
  vmdktool.8.gz using Groff. Since the final vmdktool.8.gz is never not
  installed anyway (the install target always installs the original
  vmdktool.8), it is better to just change the ALL_TARGET to vmdktool directly.
  This way we do not add dependencies to the build phase.
- Set WWW to give users at least some information, even though the project does
  not have its official homepage.

Test Plan

• make test now works
• There is one less error message in the build log thanks to the ALL_TARGET change.