Here is a mapping from old names to new names, as best as I know. This can help you to recompile applications which were ported to Linux with the old structure member names.

Old name	New name
_base	_IO_buf_base
_ebuf	_IO_buf_end
_eback(?)	_IO_base
_gbase	_IO_buf_base
_gptr	_IO_read_ptr
_egptr	_IO_read_end
_pbase	_IO_write_base
_pptr	_IO_write_ptr
_epptr	_IO_write_end