Use clang as host compiler on android with gn too.

Use clang as host compiler on android with gn too.

This ports https://codereview.chromium.org/430383002/ to gn.
Patch from brettw in https://codereview.chromium.org/385823002/ , this just
activates it.

BUG=360311
[email protected]

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287416

[brettw, 2014-08-04 21:50:35]

lgtm

[Nico, 2014-08-04 22:45:39]

The CQ bit was checked by [email protected]

[commit-bot: I haz the power, 2014-08-04 22:46:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/[email protected]/426533003/1

[Nico, 2014-08-05 00:13:29]

Committed patchset #1 manually as 287416 (presubmit successful).