_PTHREADS in libg++ @ Linux. linking problems.

[Yotam Medini <yotam at blueneptune dot com>]

After installing version 2.8.0 of g++ and libstdc++/libg++,
under Linux 2.0.32 (RedHat 5.0 distribution)
I noticed that when using it to compile and link, I get linking
problems such as attached below.

Adding -D_PTHREADS to the g++ compilation flags solved these problems!
I wonder:
  * Is it an installation problem of libstdc++?
    Should the library contain instantiations of both _PTHREADS 
    defined or undefined variants?
  * Should _PTHREADS be a user preference?

-- yotam
 .--------------------------------------------------------------------------,
<  Yotam Medini   yotam@blueneptune.com  http://www.blueneptune.com/~yotam/  >
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mabat.o:/home/local/gcc28/include/g++/stl_alloc.h:425: undefined reference to `basic_string<char, string_char_traits<char>, __default_alloc_template<false, 0> >::replace(unsigned int, unsigned int, basic_string<char, string_char_traits<char>, __default_alloc_template<false, 0> > const &, unsigned int, unsigned int)'
mabat.o: In function ...
/home/local/gcc28/include/g++/stl_alloc.h:421: undefined reference to `__dl__Q2t12basic_string3ZcZt18string_char_traits1ZcZt24__default_alloc_template2b0i03RepPv'
mabat.o: In function ...
/home/local/gcc28/include/g++/stl_vector.h:79: undefined reference to `basic_string<char, string_char_traits<char>, __default_alloc_template<false, 0> >::nilRep'