Besides libtool-2.4.6-r1 being changed a lot, it seems to disable libltdl, and instead depend on dev-libs/libltdl. I fear the patches that are in libtool now patching libltdl need to be applied to dev-libs/libltdl, but I'm not sure. That ebuild is very shallow/simple at the moment. This currently blocks updating to libtool-2.4.6.
dev-libs/libltdl appears to just install the libltdl.so thinghy, which should be pretty much platform OK (we apply no patches to its sources it seems).