When emerging dev-cpp/libpqpp the ebuild makes a symbolic link /usr/lib/postgresql/libpq++.so to tmp/portage/libpqpp-4.0-r2/image//usr/lib/postgresql/libpq++.so.4.0 instead of /usr/lib/postgresql/libpq++.so.4.0
Resolved in libpqpp-4.0-r3