[google][4.6]Make option -freorder-functions= invoke function reordering linker plugin (issue 5825054)

[Sriraman Tallam]

Updated doc/invoke.texi and submitted.

Thanks,
-Sri.

On Sat, Mar 17, 2012 at 11:58 PM,  <davidxl@google.com> wrote:
>
> Ok for google branches after updating the doc/invoke.texi file.
>
> David
>
>
> http://codereview.appspot.com/5825054/