Disable arm-gepopt by default

[Tim Northover]

On 20 April 2015 at 19:03, Gerolf Hoflehner <ghoflehner at apple.com> wrote:
> from a birds view this optimization needs more work, quite possibly more so
> in other passes rather than the algorithm itself.  In our environment we
> haven’t seen *any* gains from it. Could you and/or Hao take this on after
> the code is disabled/backed out?

To be fair, the chances are we've only tested it on a single CPU
family; and from what I see in this thread only in artificial
benchmarks. I have a great deal of sympathy with James's position, and
think "we're disabling it, you & Hao get to pick up the pieces" is a
bit extreme.

Tim.