arm "neon"

[David Miller]

From: Michael Mohr <mohr at linuxcertified.com>
Date: Mon, 14 Jan 2013 12:10:30 -0800

> At least for Android this may not be an option.  It provides a
> "cpufeatures" library for use at runtime.  I suggest using a configure
> option which explicitly enables this, and disable it otherwise.

I really think at some point soon GMP should use IFUNC relocations,
rather than be required to be built for a specific cpu target to get
the most optimal implementations of all of these routines.

To me this seems more important than any particular cpu specific
optimization at this point.