PATCH: Add --enable-__cxa_atexit

[Jack Howarth]

Mark,
   So then you accept HJ Lu's patch with the removal of the section
which builds libstdc++v3 with -fno-use-cxa-atexit? I also wonder if
we shouldn't have the default for --enable-use__cxa_atexit set to
yes? You seem to be saying that using -fno-use-cxa-atexit will lead
to nasty breakage when applied to libstdc++v3...however that is
effectively what the current gcc 3.1.1 builds are doing prior to
HJ's patch. 
             Jack
ps I don't think your message made it to the list...you cc'd 
gcc@gcc.gnu.og instead of gcc@gcc.gnu.org.