Fix build on gcc-based architectures:
//usr/local/lib/libexiv2.so.26: undefined reference to `VTT for std::__cxx11::basic_stringstream<char, std::char_traits<char>, std::allocator<char> >@GLIBCXX_3.4.21'
While here, pet portlint.
Approved by: portmgr (tier-2 blanket)