Removing -fssa

[Mark Mitchell]

I'd like to remove -fssa from the mainline and disable it on the
branch.

The manual already documents this switch as not ready for production
use, and the tree-ssa branch is what we really want for this
functionality.  Having it on the mainline and branch is just creating
confusion for users, and bogus PRs in the database.

Any objections?

--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com