Fix hppa/ia64/microblaze executable stack default (bug 22156)

[Carlos O'Donell]

On 09/19/2017 08:54 AM, Andreas Schwab wrote:
> It's the absence of the note that is relevant here.

It can't be safe to override this?

This breaks backwards compatibility with old binaries that don't have PT_GNU_STACK
but need executable stacks?

I thought perhaps we were arguing to make old binaries
safer, at the risk of breaking some of them.

-- 
Cheers,
Carlos.