virtual/glu should have a means of having no deps when built for mingw-w64, as dev-util/mingw64-runtime includes the needed glu headers and import libraries. One would think that dep'ing on on mingw64-runtime, but it is invisible to the cross emerge and that's not an option in this case.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=d391a226e006654e6d493b52542c2a38998d3442 commit d391a226e006654e6d493b52542c2a38998d3442 Author: Marty E. Plummer <hanetzer@startmail.com> AuthorDate: 2018-04-12 12:15:26 +0000 Commit: Sergei Trofimovich <slyfox@gentoo.org> CommitDate: 2018-04-15 18:51:22 +0000 virtual/glu: add dev-util/mingw64-runtime Closes: https://bugs.gentoo.org/621768 Package-Manager: Portage-2.3.28, Repoman-2.3.9 virtual/glu/glu-9.0-r2.ebuild | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)