[gold] enable sorting of text sections with the same prefix

[Cary Coutant]

> The attached patch enables sorting output sections by name (except for
> special output sections like ctors, dtors etc.) when
> --sort-section=name option is specified (like in bfd).
>
> make check-gold passes for me on x86_64 linux. Is it OK for trunk?

This is OK. I've committed it to trunk on your behalf.

Thanks for working on this.

-cary