Add Load2/store2 to Sk4x (dumb impl for now)

Add Load2/store2 to Sk4x (dumb impl for now)

patch from issue 1001003002 at patchset 1 (http://crrev.com/1001003002#ps1)

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/422677ceab3908060917adf4181aaebb48bbaf41

[reed1, 2015-03-18 19:47:45]

reed@google.com changed reviewers:
+ msarett@google.com, mtklein@google.com

[reed1, 2015-03-18 19:47:46]

can I land this, and then we back-fill with "faster" impls later?

[reed1, 2015-03-18 19:47:55]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-03-18 19:48:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1001453006/1

[commit-bot: I haz the power, 2015-03-18 19:48:05]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-03-19 01:48 UTC

[msarett, 2015-03-18 19:56:10]

lgtm

Mike had a CL that implemented Load2/Store2 for SSE that I gave an lgtm.  Maybe
he will integrate with this?

I haven't had a chance to back-fill for Neon yet, but I haven't forgotten.

[commit-bot: I haz the power, 2015-03-18 19:56:50]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/422677ceab3908060917adf4181aaebb48bbaf41

[mtklein, 2015-03-18 19:57:26]

Right, the one I sent out will be faster, but this is fine to start with if you
just want to get an API settled.

[reed1, 2015-03-18 20:44:27]

On 2015/03/18 19:57:26, mtklein wrote:
> Right, the one I sent out will be faster, but this is fine to start with if
you
> just want to get an API settled.

exactly, I wanted to have the api available for use-case testing.