eix seems to have a configure check to determine whether --as-needed can be used. See also bug #209239 (a bit lenghty bug). Whether or not to use --as-needed, is a user preference, and should not be forced upon the user by the configure script. Hence the ebuild should pass --disable-as-needed to econf, to disable this autodetection.
The configure switch will be gone in the upcoming release of eix.
Fixed in eix-0.12.2, thanks!