[RFA/dwarf2] better check for external references

[Jim Blandy]

Joel Brobecker <brobecker@adacore.com> writes:
> 2006-02-04  Joel Brobecker  <brobecker@adacore.com>
>
>         * dwarf2read.c (partial_die_info): Add field has_byte_size.
>         (add_partial_symbol): Correct identification of external references.
>         (process_structure_scope): Likewise.
>         (read_partial_die): Handle DW_AT_byte_size attribute.
>
> 2006-02-04  Joel Brobecker  <brobecker@adacore.com>
>
>         * gdb.base/nofield.c: New file.
>         * gdb.base/nofield.exp: New testcase.
>
> Tested on x86-linux. No regressions. nofield.exp is an all PASS
> after the patch is applied (had a couple of FAILs before).
>
> OK to apply?

This looks great!  Please do.