* Implement support for weak symbols. This solves the "___error" undefined
problem on 3.0-CURRENT systems.
* look for crt0.o in /usr/lib/aout on 3.0-CURRENT systems.
default for FreeBSD. The standard exception implementation reliably
dumps core under FreeBSD. Users can put "-fno-sjlj-exceptions" on
the command line if they really want to override the new default.
Configure with "--with-gnu-as" and "--with-gnu-ld".
Define "__FreeBSD__" as 3.