Split rsqrt into rsqrt{0,1,2}, with increasing cost and precision on ARM

Split rsqrt into rsqrt{0,1,2}, with increasing cost and precision on ARM

This is a logical no-op.  Everything was using the equivalent of rsqrt1() before, and is now after.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/9de16283fdc8cc0d31a84f503578d0ecea4e8297

CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Ubuntu-GCC-Arm64-Debug-Android-Trybot

Committed: https://skia.googlesource.com/skia/+/d7c014ff03d44d3ed7a6a2ddca59621a7e98f739

[mtklein_C, 2015-04-27 19:12:02]

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

[mtklein, 2015-04-27 19:32:37]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-27 19:32:44]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109913002/20001

[commit-bot: I haz the power, 2015-04-27 19:36:15]

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

[commit-bot: I haz the power, 2015-04-27 19:36:16]

Dry run: This issue passed the CQ dry run.

[reed1, 2015-04-27 20:50:12]

lgtm

[mtklein, 2015-04-27 20:50:45]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-04-27 20:51:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109913002/20001

[commit-bot: I haz the power, 2015-04-27 20:51:31]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/9de16283fdc8cc0d31a84f503578d0ecea4e8297

[mtklein, 2015-04-27 20:55:28]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1105233003/ by mtklein@google.com.

The reason for reverting is: arm64 typos.

[mtklein, 2015-04-27 20:57:53]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-04-27 20:57:53]

The patchset sent to the CQ was uploaded after l-g-t-m from reed@google.com
Link to the patchset: https://codereview.chromium.org/1109913002/#ps40001
(title: "arm64 typos")

[commit-bot: I haz the power, 2015-04-27 20:58:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109913002/40001

[commit-bot: I haz the power, 2015-04-27 21:22:36]

Committed patchset #3 (id:40001) as
https://skia.googlesource.com/skia/+/d7c014ff03d44d3ed7a6a2ddca59621a7e98f739