swfdec-0.5.5 has incorrect RDEPs on alsa. RDEPEND="... >=media-libs/alsa-lib-1.0.12 ... alsa? ( >=media-libs/alsa-lib-1.0 ) " . . . yeah, it shouldn't do that. It still builds with ALSA even if the USE flag is disabled, because someone left in the forced depend from the earlier 0.5.4-r1 ebuild. Looks like someone forgot to clean this up. First noticed it here: http://forums.gentoo.org/viewtopic-p-5009840.html#5009840
fix is in overlay and shall land in portage when we get our >0.6 release.
That dep is gone.