Shared library annoyance with gcc-3_0-branch

[dewar@gnat.com]

<<RTH means that only one copy of the code and data must be linked in.
This has nothing to do with multithreading.

This restriction is unfortunate though, since it never was the case that
the gcc library had such state, so it was perfectly fine to have multiple
copies.  I really think we should have moved the exception stuff into a
separate library.
>>

Well anything with state is worrisome from a multi-threading point of view,
that's why I asked, so saying that "this has nothing to do with
multithreading" seems a bit sweeping.

If the exception handling uses any global variables, one hopes these
are properly protected for the multi-threading case.