Thought I's pass this along to someone more knowledgable about these things :

Just tried to compile simgear and got this error :
include/c++/4.4.0/ext/atomicity.h:46: undefined reference to `__sync_fetch_and_add_4'

Got it to finish compiling by configuring like this:
./configure CXXFLAGS="-march=i686" ...

after some searching made it clear that i386 isnt supported anymore.
Cheers,
Syd