gn: Don't build sse3 code in skia with -msse4.1.

gn: Don't build sse3 code in skia with -msse4.1.

Else the compiler can create SSE4.1 instructions for the SSE3 files, but we
only check for SSE3 when running that code.  So the code might crash with
"unknown instruction" when running on a processor that has SSE3 but not SSE4.

This matches what the gyp build does.

Depends on https://codereview.chromium.org/1161853008/

BUG=496512
Committed: https://crrev.com/8e8785dd45bee98a19ce01dd8ea3a4fc64a2e236
Cr-Commit-Position: refs/heads/master@{#333171}

[Nico, 2015-06-05 19:14:00]

thakis@chromium.org changed reviewers:
+ brettw@chromium.org

[Nico, 2015-06-05 19:14:00]

This is a bit ugly, but together with the other two CLs it's still a net
reduction in complexity.

[brettw, 2015-06-05 20:18:47]

lgtm

[Nico, 2015-06-05 22:26:54]

The CQ bit was checked by thakis@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-05 22:27:51]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160253011/20001

[commit-bot: I haz the power, 2015-06-05 23:07:35]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-05 23:07:38]

Dry run: This issue passed the CQ dry run.

[Nico, 2015-06-05 23:08:16]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-06-05 23:10:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160253011/20001

[commit-bot: I haz the power, 2015-06-05 23:16:18]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-05 23:17:47]

Patchset 2 (id:??) landed as
https://crrev.com/8e8785dd45bee98a19ce01dd8ea3a4fc64a2e236
Cr-Commit-Position: refs/heads/master@{#333171}