Update Mac build instructions for installing command line tools.

Update Mac build instructions for installing command line tools.

Mac builds require OS X 10.9; since 10.9 it is possible to install the
command line tools using xcode-select. The command line tools aren't
always available in Xcode Preferences > Downloads.

BUG=none

Committed: https://crrev.com/a4e4c9973eceb766276d54970367532ef134b949
Cr-Commit-Position: refs/heads/master@{#395431}

[dominicc (has gone to gerrit), 2016-05-19 07:46:58]

Description was changed from

==========
Update Mac build instructions for installing command line tools.

Mac builds require OS X 10.9; since 10.9 it is possible to install the
command line tools using xcode-select. The command line tools aren't
always available in Xcode Preferences > Downloads.
==========

to

==========
Update Mac build instructions for installing command line tools.

Mac builds require OS X 10.9; since 10.9 it is possible to install the
command line tools using xcode-select. The command line tools aren't
always available in Xcode Preferences > Downloads.

BUG=none
==========

[dominicc (has gone to gerrit), 2016-05-19 07:46:58]

dominicc@chromium.org changed reviewers:
+ tfarina@chromium.org

[dominicc (has gone to gerrit), 2016-05-19 07:47:06]

PTAL

[dominicc (has gone to gerrit), 2016-05-22 23:05:06]

dominicc@chromium.org changed reviewers:
+ erikchen@chromium.org
- tfarina@chromium.org

[dominicc (has gone to gerrit), 2016-05-22 23:05:18]

PTAL, quick doc update.

[erikchen, 2016-05-23 17:09:15]

lgtm

[dominicc (has gone to gerrit), 2016-05-23 21:20:24]

The CQ bit was checked by dominicc@chromium.org

[commit-bot: I haz the power, 2016-05-23 21:20:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1997593002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1997593002/1

[commit-bot: I haz the power, 2016-05-23 22:08:13]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-05-23 22:10:56]

Description was changed from

==========
Update Mac build instructions for installing command line tools.

Mac builds require OS X 10.9; since 10.9 it is possible to install the
command line tools using xcode-select. The command line tools aren't
always available in Xcode Preferences > Downloads.

BUG=none
==========

to

==========
Update Mac build instructions for installing command line tools.

Mac builds require OS X 10.9; since 10.9 it is possible to install the
command line tools using xcode-select. The command line tools aren't
always available in Xcode Preferences > Downloads.

BUG=none

Committed: https://crrev.com/a4e4c9973eceb766276d54970367532ef134b949
Cr-Commit-Position: refs/heads/master@{#395431}
==========

[commit-bot: I haz the power, 2016-05-23 22:10:57]

Patchset 1 (id:??) landed as
https://crrev.com/a4e4c9973eceb766276d54970367532ef134b949
Cr-Commit-Position: refs/heads/master@{#395431}