If you are seeing this error, which affects only -current, it is because the libstdc++ configuration was slightly wrong for a few months. Fixing involved removing a symbol, so you get an undefined reference.
If you see: /usr/pkgobj/graphics/gimp/work/.buildlink/lib/libexiv2.so: undefined reference to `logf@GLIBCXX_3.4' Do: pkg_info -Fe /usr/pkg/lib/libexiv2.so To find which package is affected by the ABI breakage, and rebuild it to get correct references.