thread support on by default ?

[Stefan Seefeld <seefeld at sympatico dot ca>]

with multi threaded programs becoming more widespread, what about 
switching the --enable-threads
flag on by default ? How much overhead does it produce for non-MT programs ?

Right now we have to require people to make sure that their compiler is 
compiled with --enable-threads
to correctly build our project. As it is often unclear what flags a 
binary distributed compiler was compiled
with, that often means that people have to recompile the compiler by 
themselfs.
(I'm specifically talking about the berlin project, where we make heavy 
use of multi-threading as well as exceptions).

Thanks,    Stefan