If "WANT_DWARF2_UNWIND" you get it. Note that this is a different C++ ABI
than the FreeBSD default. So you will need to recompile all your C++ apps
that uses exceptions if you turn this on. I am adding it here for Yahoo!'s
use and for those that want to be early adopters to what I will make as the
default with the GCC 3.0 import.