clang/win/gn: Pass -msse flags to clang-cl.exe

clang/win/gn: Pass -msse flags to clang-cl.exe

This is a port of https://codereview.chromium.org/504893003/ to gn.

(AVX is already correct, see https://codereview.chromium.org/866273003/)

BUG=491209, 82385
R=tomfinegan@chromium.org

Committed: https://chromium.googlesource.com/chromium/deps/libvpx/+/a43631169b4200f2000c8cfa82404ce507e31486

[Nico, 2015-06-04 20:17:10]

thakis@chromium.org changed reviewers:
+ johannkoenig@google.com, tomfinegan@chromium.org

[Nico, 2015-06-04 20:17:10]

First to stamp wins!

[Tom Finegan, 2015-06-04 20:23:02]

I'm a winner! \o/

lgtm

[Johann, 2015-06-04 20:24:30]

On 2015/06/04 20:23:02, Tom Finegan wrote:
> I'm a winner! \o/
> 
> lgtm

Winner has to land the patch for Nico :P

[Nico, 2015-06-04 20:24:31]

The CQ bit was checked by thakis@chromium.org

[Nico, 2015-06-04 20:25:06]

Committed patchset #1 (id:1) manually as
a43631169b4200f2000c8cfa82404ce507e31486 (presubmit successful).

[Nico, 2015-06-04 20:25:32]

Congrats!

Looks like `git cl land` worked for me:
https://chromium.googlesource.com/chromium/deps/libvpx/+/a43631169b4200f2000c...

[Johann, 2015-06-04 20:25:42]

On 2015/06/04 20:25:06, Nico wrote:
> Committed patchset #1 (id:1) manually as
> a43631169b4200f2000c8cfa82404ce507e31486 (presubmit successful).

ohhh nice! maybe no one else who has tried is a full committer.

[Johann, 2015-06-04 20:26:34]

On 2015/06/04 20:25:32, Nico wrote:
> Congrats!
> 
> Looks like `git cl land` worked for me:
>
https://chromium.googlesource.com/chromium/deps/libvpx/+/a43631169b4200f2000c...

Good because my attempt to move libvpx out of DEPS has stalled (going on vaca
soon, will dig into it sometime later)

[Johann, 2015-06-04 20:26:36]

On 2015/06/04 20:25:32, Nico wrote:
> Congrats!
> 
> Looks like `git cl land` worked for me:
>
https://chromium.googlesource.com/chromium/deps/libvpx/+/a43631169b4200f2000c...

Good because my attempt to move libvpx out of DEPS has stalled (going on vaca
soon, will dig into it sometime later)