Supporting --enable-version-specific-runtime-libs

[Benjamin Kosnik]

Mark.

Thanks for this work. I'm interested in getting this into current CVS,
and am willing to to the work based on your patch. A couple of
comments:

1) I need a ChangeLog entry

2) The USE_LIBDIR vs USING_CROSS_COMPILER change seems a bit
   gratuitous. USE_LIBDIR is pretty much what other libraries use
   (libjava, for instance) and I'd like to try and keep libstdc++-v3
   in a consistent state WRT other GNU libraries. Or, is there
   something that I'm missing?

3) can you provide a patch to docs/configopts.html that explains the
   various configure bits?

thanks,
benjamin