New AIX template failures

[Benjamin Kosnik]

>3983-fstram.cc includes:
>
>template
>  std::basic_filebuf<unsigned char>::int_type
>  std::basic_filebuf<unsigned char>::_S_pback_size;
>
>The error message is:
>
>std::basic_filebuf<unsigned char, std::char_traits<unsigned char>>::_S_pback_size
>
>There seem to be a different number of parameters.

... the second template argument is a default, for char_traits<_T>. The
instantiation in the file should work.

Looks like a compiler bug to me.

-benjamin