mac: Actually include libc++ headers in clang package.

mac: Actually include libc++ headers in clang package.

Follow-up to r270095 where I tried to do this already, but wasn't quite
successful. (It worked on my box, but nowhere else.)

BUG=400088
R=hans@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287585

[Nico, 2014-08-05 18:14:14]

:-/

[hans, 2014-08-05 18:19:23]

lgtm

Why did it work on your machine if you weren't tar'ing up the include/ dir?

[Nico, 2014-08-05 18:21:32]

On 2014/08/05 18:19:23, hans wrote:
> lgtm
> 
> Why did it work on your machine if you weren't tar'ing up the include/ dir?

'cause I never used the tar. My third_party/llvm-build/Release+Asserts had bin,
lib, and include subdirectories, so it was happy. And since I usually build the
tgzs on my Mac, I rarely download them again (clang thinks it's up-to-date since
I built it locally at the same revision.)

[Nico, 2014-08-05 20:42:18]

Committed patchset #1 manually as 287585 (presubmit successful).