NaCl/GYP: remove references to prep_toolchain.

NaCl/GYP: remove references to prep_toolchain in ICU.

prep_toolchain is now a no-op.

BUG=456902
R=jshin@chromium.org

Committed: https://chromium.googlesource.com/chromium/deps/icu/+/f8c0e585b0a046d83d72b5d37356cb50d5b2031a

[Nick Bray (chromium), 2015-04-20 21:42:40]

ncbray@chromium.org changed reviewers:
+ jshin@chromium.org

[Nick Bray (chromium), 2015-04-20 21:43:06]

Is it appropriate to patch this file directly, or do I need to do is upstream
somewhere?

[jungshik at Google, 2015-04-21 13:08:20]

On 2015/04/20 21:43:06, Nick Bray (chromium) wrote:
> Is it appropriate to patch this file directly, or do I need to do is upstream
> somewhere?

It's ours only so that changing directly is fine. 
LGTM

[Nick Bray (chromium), 2015-04-21 15:58:22]

The CQ bit was checked by ncbray@chromium.org

[commit-bot: I haz the power, 2015-04-21 16:03:10]

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

[commit-bot: I haz the power, 2015-04-21 16:03:11]

Commit queue rejected this change because it did not recognize the base URL.
Please commit your change manually.

[Nick Bray (chromium), 2015-04-21 16:07:59]

Committed patchset #1 (id:1) manually as
f8c0e585b0a046d83d72b5d37356cb50d5b2031a (presubmit successful).

[jungshik at Google, 2015-04-21 18:59:13]

On 2015/04/21 16:07:59, Nick Bray (chromium) wrote:
> Committed patchset #1 (id:1) manually as
> f8c0e585b0a046d83d72b5d37356cb50d5b2031a (presubmit successful).

Nick, just in case, please roll ICU in DEPS. :-) (perhaps, you've already done
it).

[Nick Bray (chromium), 2015-04-21 19:05:38]

I was going to do 3 related DEPS rolls at once, currently hung up on this one:
https://webrtc-codereview.appspot.com/51699004/