[v3] weak instantiations for AIX

[David Edelsohn]

	The 3983-fstream.cc tests need the templates to be instantiated
with "unsigned char" not "gnu_char_type".  With the following change, the
two tests compile, link, and run.

David


	* testsuite/27_io/basic_istream/sentry/char/3983-fstream.cc:
	Change basic_streambuf instantiation to "unsigned char".

Index: 3983-fstream.cc
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/testsuite/27_io/basic_ostream/sentry/char/3983-fstream.cc,v
retrieving revision 1.2
diff -c -p -r1.2 3983-fstream.cc
*** 3983-fstream.cc	11 Apr 2003 17:25:20 -0000	1.2
--- 3983-fstream.cc	12 Apr 2003 01:37:21 -0000
*************** template 
*** 153,160 ****
    std::basic_string<unsigned char>::_Rep::_S_terminal;
  
  template
!   std::basic_streambuf<gnu_char_type>::int_type
!   std::basic_streambuf<gnu_char_type>::_S_pback_size;
  #endif
  
  int main()
--- 153,160 ----
    std::basic_string<unsigned char>::_Rep::_S_terminal;
  
  template
!   std::basic_streambuf<unsigned char>::int_type
!   std::basic_streambuf<unsigned char>::_S_pback_size;
  #endif
  
  int main()
Index: 3983-fstream.cc
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/testsuite/27_io/basic_istream/sentry/char/3983-fstream.cc,v
retrieving revision 1.2
diff -c -p -r1.2 3983-fstream.cc
*** 3983-fstream.cc	11 Apr 2003 17:25:20 -0000	1.2
--- 3983-fstream.cc	12 Apr 2003 01:37:41 -0000
*************** template 
*** 182,189 ****
    std::basic_string<unsigned char>::_Rep::_S_terminal;
  
  template
!   std::basic_streambuf<gnu_char_type>::int_type
!   std::basic_streambuf<gnu_char_type>::_S_pback_size;
  #endif
  
  int main()
--- 182,189 ----
    std::basic_string<unsigned char>::_Rep::_S_terminal;
  
  template
!   std::basic_streambuf<unsigned char>::int_type
!   std::basic_streambuf<unsigned char>::_S_pback_size;
  #endif
  
  int main()