CMake bot script

CMake bot script

 - Add CMake v3.3.1 (latest) to DEPS.
 - Add cmake/bot-cmake.sh to bootstrap CMake then build Skia using that.

Works on my Mac and Linux box, both with no system CMake installation.

CMake will be ~100M on disk.  The first bootstrap takes a couple minutes,
and a no-op re-run of bot-cmake.sh takes 15-20 seconds.  I thought about
having bot-cmake.sh fetch CMake instead of DEPS, but I'm not sure I can
handle updates, etc. as robustly as it can.

This will only work on Linux and Mac.  CMake requires an older CMake on
Windows.  It doesn't have an equivalent ./bootstrap there.  Will have to 
think about how Windows bots will work!

BUG=skia:4269
Committed: https://skia.googlesource.com/skia/+/a22eabedef0cc1256f8c60e58e7a1cbd0bd1db9b

[mtklein_C, 2015-09-14 16:48:35]

mtklein@chromium.org changed reviewers:
+ borenet@google.com

[borenet, 2015-09-14 16:54:13]

LGTM, but I think I'd prefer the script be called "cmake_build", following the
example of platform_tools/android/bin/android_make, chromeos, etc.

[mtklein_C, 2015-09-14 16:56:12]

On 2015/09/14 16:54:13, borenet wrote:
> LGTM, but I think I'd prefer the script be called "cmake_build", following the
> example of platform_tools/android/bin/android_make, chromeos, etc.

Done.

[mtklein_C, 2015-09-14 16:56:14]

The CQ bit was checked by mtklein@chromium.org

[mtklein_C, 2015-09-14 16:56:14]

The patchset sent to the CQ was uploaded after l-g-t-m from borenet@google.com
Link to the patchset: https://codereview.chromium.org/1339603003/#ps60001
(title: "comment")

[commit-bot: I haz the power, 2015-09-14 16:56:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1339603003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1339603003/60001

[commit-bot: I haz the power, 2015-09-14 17:02:53]

Committed patchset #4 (id:60001) as
https://skia.googlesource.com/skia/+/a22eabedef0cc1256f8c60e58e7a1cbd0bd1db9b