When installing sys-apps/dbus with the ABI_X86_32 flag, dev-libs/expat was not pulled in to recompile with the same flag. This caused the build to fail during the configuration phase (could not find expat).
Please attach the entire build log to this bug report. Please post your `emerge --info` output in a comment.
Created attachment 512654 [details] emerge --info
@Will S: you forgot to attach the build log. You can find it in /var/log/portage.