[turbofan] Split ControlEquivalence implementation and add trace flag.

[turbofan] Split ControlEquivalence implementation and add trace flag.

Split interface and implementation of ControlEquivalence and add a
dedicated trace flag --trace-turbo-ceq to make it reusable outside the
scheduler.

R=jarin@chromium.org

Committed: https://crrev.com/d641cc457cdf07fa10d09de2f61fbbbfb3c36adb
Cr-Commit-Position: refs/heads/master@{#27862}

[Benedikt Meurer, 2015-04-16 04:23:12]

Hey Jaro,

Reducing linking/compile/inlining overhead for ControlEquivalence, and tracing
independent of scheduler. Otherwise unchanged. Please take a look.

Thanks,
Benedikt

[Jarin, 2015-04-16 06:02:58]

lgtm

[Benedikt Meurer, 2015-04-16 06:03:17]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-04-16 06:03:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1056093005/1

[commit-bot: I haz the power, 2015-04-16 06:04:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-16 06:05:00]

Patchset 1 (id:??) landed as
https://crrev.com/d641cc457cdf07fa10d09de2f61fbbbfb3c36adb
Cr-Commit-Position: refs/heads/master@{#27862}