I've just commited an update to devel/libtool that should bring back
support for C++ on a.out toolchains, i.e. link in /usr/lib/c++rt0.o
appropriately. All packages that use the old --cplusplus option and
USE_PKGLIBTOOL can now be changed to USE_LIBTOOL. The --cplusplus option
has not been added back as there is some magic in ltconfig.in that
removes the need for it.

Please let me know if you have any problems with it.

Nick