dl_iterate_phdr() deadlock patch

[Tom Tromey]

>>>>> "Hans" == Boehm, Hans <hans_boehm@hp.com> writes:

Hans> This patch is extracted from my current GC tree.  I would like
Hans> to check it into both the trunk and 3.3.  It should do 4 things:

Thanks.  I'm still hoping to import the new GC, but it seems less and
less likely before 3.3 due to lack of time.

This patch was the major thing we wanted from the import.  So let's
put it in to 3.3 and 3.4.  It won't hurt if I'm able to do the import,
and it will help a lot of I'm not able.

Hans> Question: Is it currently true that GC_dlopen can only be called
Hans> from one thread at a time?

Yes, we synchronize around ltdl calls.

Well, SharedLibLoader isn't synchronized, but that isn't used much and
has some bugs anyway.  Though this reminds me I need to fix up my big
solib: patch to make sure the dlopen is synchronized properly.  I put
this on my to-do list.

Tom