add SK_SUPPORT_LEGACY_IMAGEFILTER_CTM to guard skia change

add SK_SUPPORT_LEGACY_IMAGEFILTER_CTM to guard skia change

see https://codereview.chromium.org/1140943004/

BUG=
NOTRY=True
just adds a new flag for future cls

Committed: https://crrev.com/53ff0e3b5bf6b2aa48d7300d1aef1f8a30aa98a1
Cr-Commit-Position: refs/heads/master@{#329841}

[reed1, 2015-05-14 12:31:17]

reed@google.com changed reviewers:
+ robertphillips@chromium.org, senorblanco@chromium.org

[reed1, 2015-05-14 12:31:25]

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

[commit-bot: I haz the power, 2015-05-14 12:32:30]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1133403003/1

[robertphillips, 2015-05-14 12:35:19]

robertphillips@google.com changed reviewers:
+ robertphillips@google.com

[robertphillips, 2015-05-14 12:35:19]

lgtm

[reed1, 2015-05-14 12:45:39]

The CQ bit was unchecked by reed@google.com

[reed1, 2015-05-14 12:45:44]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-05-14 12:46:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1133403003/1

[reed1, 2015-05-14 13:22:03]

The CQ bit was unchecked by reed@google.com

[reed1, 2015-05-14 13:22:28]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-05-14 13:23:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1133403003/1

[commit-bot: I haz the power, 2015-05-14 13:26:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-14 13:27:55]

Patchset 1 (id:??) landed as
https://crrev.com/53ff0e3b5bf6b2aa48d7300d1aef1f8a30aa98a1
Cr-Commit-Position: refs/heads/master@{#329841}