Revert of Specialize Sk2d for ARM64

Revert of Specialize Sk2d for ARM64 (patchset #3 id:40001 of https://codereview.chromium.org/1020963002/)

Reason for revert:
https://uberchromegw.corp.google.com/i/client.skia.compile/builders/Build-Mac10.7-Clang-Arm7-Debug-iOS/builds/2441/steps/build%20most/logs/stdio

https://uberchromegw.corp.google.com/i/client.skia.compile/builders/Build-Mac10.7-Clang-Arm7-Release-iOS/builds/2424/steps/build%20most/logs/stdio

https://uberchromegw.corp.google.com/i/client.skia.compile/builders/Build-Ubuntu-GCC-Arm64-Release-Android/builds/8/steps/build%20most/logs/stdio

Original issue's description:
> Specialize Sk2d for ARM64
> 
> The implementation is nearly identical to Sk2f, with these changes:
>   - float32x2_t -> float64x2_t
>   - vfoo -> vfooq
>   - one extra Newton's method step in sqrt().
> 
> Also, generally fix NEON detection to be defined(SK_ARM_HAS_NEON).
> SK_ARM_HAS_NEON is not being set on ARM64 bots right now (nor does the compiler
> seem to set __ARM_NEON__), so this CL fixes everything up.
> 
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/e57b5cab261a243dcbefa74c91c896c28959bf09

TBR=msarett@google.com,reed@google.com,mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/c3ce1d28a53e70f4faa71f9d5bbda605b0664830

[mtklein, 2015-03-20 15:46:08]

Created Revert of Specialize Sk2d for ARM64

[commit-bot: I haz the power, 2015-03-20 15:46:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1028523003/1

[commit-bot: I haz the power, 2015-03-20 15:46:40]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/c3ce1d28a53e70f4faa71f9d5bbda605b0664830