Added an extra system include

[petewarden]

No description provided.

[petewarden]

Looks like we need one more include

[petewarden]

I also just added support for the Pi Two/Three with NEON by default to the build script. This involves an update to Eigen, the fix for tensorflow#9697

I think we should build both Pi One/Zero and Two/Three wheels, but default to the NEON-enabled ones since they're an order of magnitude faster, and most developers will be using a Pi that's capable.

I tested the two wheels by running:

import tensorflow as tf; sess = tf.Session();
tf.matmul(tf.zeros([1000,1000]), tf.zeros([1000, 1000])).eval(session=sess)

and timing the matmul call. On my Pi Three, the non-NEON install took seven seconds to run that call, but only about 500ms with the NEON wheel installed.

Completed wheels are available for testing at https://drive.google.com/file/d/0B7tFa8eBGIw-V0xKMG5Zem5rczQ/view?usp=sharing

There's a gist with my steps for running the build process on a clean Ubuntu 14.04 Docker image here (which I'm hoping we can turn into a CI build script to run nightly):

https://gist.github.com/petewarden/6aa9650fe72d88889d24efd76598f8cb

[ebrevdo]

is this change necessary / will it have side effects?