In BUILD.public, specify alwayslink for skia library.

In BUILD.public, specify alwayslink for skia library.

Some Skia classes use SkTRegistry, which requires the source files be linked in order to be registered.

Also replace "*CG*" with "SkImageDecoder_CG.cpp" for clarity.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/9dbec092512ca2759b46e24850ffde40dee3029f

[dogben, 2015-10-30 17:44:39]

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

[commit-bot: I haz the power, 2015-10-30 17:44:49]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1405023013/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1405023013/1

[commit-bot: I haz the power, 2015-10-30 17:55:41]

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

[commit-bot: I haz the power, 2015-10-30 17:55:42]

Dry run: This issue passed the CQ dry run.

[dogben, 2015-10-30 17:57:30]

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

[mtklein, 2015-11-01 22:29:21]

lgtm

[dogben, 2015-11-02 13:43:06]

The CQ bit was checked by benjaminwagner@google.com

[commit-bot: I haz the power, 2015-11-02 13:43:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1405023013/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1405023013/1

[commit-bot: I haz the power, 2015-11-02 13:53:42]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/9dbec092512ca2759b46e24850ffde40dee3029f