the appearance of libc_internal_tsd_address requires a redesign, since
the existing scheme doesn't make it sensible to take the address of a
specific-data value.
New scheme is that the ThreadState structure carries not the table of
specifics, but merely a pointer to such. This is allocated from the
client-side library, thus residing in client-visible memory and so
addresses can validlyh be taken.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@1208