As above, media-video/vlc[samba] will build but hang when 'make install' attempts to run './vlc-cache-gen ../modules'. This is due to bug# 622700 (automagically enables lttng debug support).
I've just tested that, and can confirm - installing dev-util/lttng-ust and re-emerging net-fs/samba makes subsequent installation of media-video/vlc[samba] hang.
So glad I found this bug as I got the same problem.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=4f45d58fae6794d049d21f3901b66f754084fa61 commit 4f45d58fae6794d049d21f3901b66f754084fa61 Author: Andreas Sturmlechner <asturm@gentoo.org> AuthorDate: 2017-12-09 16:41:34 +0000 Commit: Andreas Sturmlechner <asturm@gentoo.org> CommitDate: 2017-12-09 16:52:39 +0000 media-video/vlc: Avoid make hang w/ net-fs/samba[debug] Closes: https://bugs.gentoo.org/624068 Package-Manager: Portage-2.3.17, Repoman-2.3.6 media-video/vlc/vlc-2.2.8.ebuild | 2 +- media-video/vlc/vlc-2.2.9999.ebuild | 2 +- media-video/vlc/vlc-3.0.9999.ebuild | 2 +- media-video/vlc/vlc-9999.ebuild | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-)