The openswan-2.6.29 tries to install to /usr/lib/ipsec instead of /usr/lib64/ipsec on amd64. I will submit a patch to the ebuild that uses get_libdir to fix this. I have been using this patched version with no problems.
Created attachment 253693 [details, diff] Patch that ensures the ebuild does not fail the multilib-strict check.
Fixed in openswan-2.6.31, thanks!