[patch] Add top-level configure support for MIPS target in gold

[Cary Coutant]

>         * configure (--enable-gold): Add mips*-*-*.
>         * configure.ac: Regenerate.

Sorry, these are backwards. Will fix before commit.

         * configure.ac (--enable-gold): Add mips*-*-*.
         * configure: Regenerate.

-cary