Disable arm-gepopt by default

[Tim Northover]

On 20 April 2015 at 20:34, Gerolf Hoflehner <ghoflehner at apple.com> wrote:
> It shouldn’t come across as ‘extreme’.

The "extreme" part wasn't so much the tentative disabling as "Could
you and/or Hao take this on after the code is disabled/backed out?". I
realise it wasn't an ultimatum, but it could very easily turn into
"we're washing our hands of this", which I'd object to.

I assume the pass was committed with some kind of metric that it
improved, and now we have a counter-example. It's down to everyone to
decide what the best way to proceed is.

Cheers.

Tim.