PPC: Remove register index/code indirection

PPC: Remove register index/code indirection

Port 5cf1c0bcf6f10ff61a95a00fa302eeee7c390885

Original commit message:
    Previous to this patch, both the lithium and TurboFan register
    allocators tracked allocated registers by "indices", rather than
    the register codes used elsewhere in the runtime. This patch
    ensures that codes are used everywhere, and in the process cleans
    up a bunch of redundant code and adds more structure to how the
    set of allocatable registers is defined.

    Some highlights of changes:

    * TurboFan's RegisterConfiguration class moved to V8's top level
      so that it can be shared with Crankshaft.
    * Various "ToAllocationIndex" and related methods removed.
    * Code that can be easily shared between Register classes on
      different platforms is now shared.
    * The list of allocatable registers on each platform is declared
      as a list rather than implicitly via the register index <->
      code mapping.

R=danno@chromium.org, bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Committed: https://crrev.com/f53fda63eb48b560bd28476158ecd5eb83c26524
Cr-Commit-Position: refs/heads/master@{#31114}

[MTBrandyberry, 2015-10-02 22:47:49]

The CQ bit was checked by mbrandy@us.ibm.com to run a CQ dry run

[commit-bot: I haz the power, 2015-10-02 22:48:03]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1381383002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1381383002/1

[commit-bot: I haz the power, 2015-10-02 23:12:53]

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

[commit-bot: I haz the power, 2015-10-02 23:12:54]

Dry run: This issue passed the CQ dry run.

[michael_dawson, 2015-10-05 13:30:21]

On 2015/10/02 23:12:54, commit-bot: I haz the power wrote:
> Dry run: This issue passed the CQ dry run.

lgtm.

[MTBrandyberry, 2015-10-05 13:39:55]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-10-05 13:40:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1381383002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1381383002/1

[commit-bot: I haz the power, 2015-10-05 13:44:13]

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

[commit-bot: I haz the power, 2015-10-05 13:44:14]

Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/6361)

[MTBrandyberry, 2015-10-05 17:14:26]

On 2015/10/05 13:44:14, commit-bot: I haz the power wrote:
> Try jobs failed on following builders:
>   v8_presubmit on tryserver.v8 (JOB_FAILED,
> http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/6361)

Waiting on approval from src/register-configuration.cc owner.

[danno, 2015-10-05 19:18:57]

src/register-configuration.cc changes lgtm

[MTBrandyberry, 2015-10-05 19:43:19]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-10-05 19:43:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1381383002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1381383002/1

[commit-bot: I haz the power, 2015-10-05 19:45:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-05 19:45:50]

Patchset 1 (id:??) landed as
https://crrev.com/f53fda63eb48b560bd28476158ecd5eb83c26524
Cr-Commit-Position: refs/heads/master@{#31114}