Move sync code to include/, switch from using platform define to a proxy header in core/

Move sync code to include/, switch from using platform define to a proxy header in core/

This fixes two problems:
  1)  #include SK_SOME_DEFINE doesn't work well for all our clients.
  2)  Things in include/ are #including things in src/, which we don't like.

TBR=reed@google.com

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/a64c48f4f929775f9c203aae809f440ac01d2c64

[mtklein_C, 2015-01-21 17:09:18]

The CQ bit was checked by mtklein@chromium.org

[mtklein_C, 2015-01-21 17:09:24]

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

[commit-bot: I haz the power, 2015-01-21 17:09:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/862983002/1

[commit-bot: I haz the power, 2015-01-21 17:13:40]

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

[commit-bot: I haz the power, 2015-01-21 17:13:40]

Try jobs failed on following builders:
  Build-Win-VS2013-x86-Debug-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Win-VS2013-x86...)

[bungeman-skia, 2015-01-21 17:48:19]

On 2015/01/21 17:13:40, I haz the power (commit-bot) wrote:
> Try jobs failed on following builders:
>   Build-Win-VS2013-x86-Debug-Trybot on client.skia.compile
>
(http://build.chromium.org/p/client.skia.compile/builders/Build-Win-VS2013-x86...)

On PS1, gyp is complaining about missing input files (it's checking that the *.h
listed as sources actually exist). Specifically,
src/ports/SkAtomics_sync.h,SkAtomics_win.h,SkMutex_pthread.h,SkMutex_win.h ,
though I suppose they should all be cleaned up.

[mtklein, 2015-01-21 17:58:58]

> On PS1, gyp is complaining about missing input files (it's checking that the
*.h
> listed as sources actually exist). Specifically,
> src/ports/SkAtomics_sync.h,SkAtomics_win.h,SkMutex_pthread.h,SkMutex_win.h ,
> though I suppose they should all be cleaned up.

Ah, thank you!

[mtklein, 2015-01-21 17:59:02]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-01-21 17:59:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/862983002/20001

[mtklein, 2015-01-21 18:06:21]

Looks like we're good here.  PTAL?

[commit-bot: I haz the power, 2015-01-21 18:07:11]

This issue passed the CQ. To commit it, remove "COMMIT=false" from
the description and try again.

[bungeman-skia, 2015-01-21 19:15:22]

Why not? lgtm

[mtklein, 2015-01-21 19:25:52]

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

[mtklein, 2015-01-21 19:25:53]

+Mike

[mtklein, 2015-01-21 20:32:16]

The CQ bit was checked by mtklein@google.com

[reed1, 2015-01-21 20:32:23]

lgtm

[commit-bot: I haz the power, 2015-01-21 20:33:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/862983002/20001

[commit-bot: I haz the power, 2015-01-21 21:13:34]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/a64c48f4f929775f9c203aae809f440ac01d2c64