The most recent change to media-sound/clementine-9999 (at the time of writing) has removed support for the 'amazoncloud' USE-flag, however a "usex amazoncloud" was overlooked on line 119 of the ebuild. Because the flag was removed from IUSE, this causes compilation to fail. Removing line 119 fixes this problem.
I can confirm both that this is an issue, and that removing line 119 of the ebuild fixes this issue.
commit 197baf91a0b62e03701f938875afe7cf025b7012 (HEAD) Author: Alexander Golubev <fatzer2@gmail.com> AuthorDate: Fri Jul 15 01:48:35 2016 +0300 Commit: Patrice Clement <monsieurp@gentoo.org> CommitDate: Sat Jul 16 11:36:39 2016 +0200 media-sound/clementine: remove a line refering to a removed USE. Gentoo-Bug: https://bugs.gentoo.org/588784 Closes: https://github.com/gentoo/gentoo/pull/1889 Signed-off-by: Patrice Clement <monsieurp@gentoo.org> media-sound/clementine/clementine-9999.ebuild | 1 - 1 file changed, 1 deletion(-) Merged. Thanks!