[turbofan] Preprocessing live ranges before register allocation.

Setting up the stage for heuristics that preprocess live ranges before register allocation, and are independent of register allocation - e.g. the deferred blocks heuristic, or the split at call sites heuristic.

Added a separate flag for this, since we intend to enable it for the linear allocator as well. Currently, the option is "on" for greedy, as a point in time to enable its testing (through the greedy allocator bots).

BUG=

Committed: https://crrev.com/c11ab6f7e51c38f1aebae783bdf6bff801389f91
Cr-Commit-Position: refs/heads/master@{#30005}

[Mircea Trofin, 2015-07-31 16:01:49]

Patchset #1 (id:1) has been deleted

[Mircea Trofin, 2015-07-31 16:03:11]

Patchset #1 (id:20001) has been deleted

[Mircea Trofin, 2015-07-31 16:07:21]

mtrofin@chromium.org changed reviewers:
+ bmeurer@chromium.org, jarin@chromium.org

[Jarin, 2015-08-03 14:46:07]

On 2015/07/31 16:09:00, Mircea Trofin wrote:

Quick update: Benedikt is on vacation; I have just returned from one. Today, I
have been mostly catching up on email and fixing/triaging urgent issues. I
should be able to review your CLs tomorrow.

[Jarin, 2015-08-04 06:10:07]

lgtm

[Mircea Trofin, 2015-08-04 14:24:32]

The CQ bit was checked by mtrofin@chromium.org

[commit-bot: I haz the power, 2015-08-04 14:24:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1256313003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1256313003/40001

[commit-bot: I haz the power, 2015-08-04 14:49:49]

Committed patchset #1 (id:40001)

[commit-bot: I haz the power, 2015-08-04 14:50:15]

Patchset 1 (id:??) landed as
https://crrev.com/c11ab6f7e51c38f1aebae783bdf6bff801389f91
Cr-Commit-Position: refs/heads/master@{#30005}