Since this week sys-devel/libtool is no more part of @system. `emerge --depclean -with-bdeps=n` now cleans autotools (including libtool) unless some package RDEPENDs on them. Please add sys-devel/libtool to RDEPEND for collectd. Alternative is to make make collectd use dlopen() instead of lt_dlopen() (same for dlsym, dlclose and dlerror). Such a patch has been submitted to collect mailing list. Reproducible: Always
Done, thanks.