[PATCH] use gold/configure.tgt to calc supported targets

[Cary Coutant]

> Rather than maintain two lists, re-use gold's target file to determine
> whether the current target is supported.
>
> 2015-04-20  Mike Frysinger  <vapier@gentoo.org>
>
>         * configure.ac: Replace $target checks with gold/configure.tgt.
>         * configure: Regenerate.

I think patches to the top-level config are supposed to be committed
in the GCC tree first, then synced to the sources tree, so you should
send your patch to gcc-patches as well. This looks OK to me, but there
may have been a reason it wasn't written this way to begin with. This
needs approval from someone who can review configure patches.

-cary