add flag to hide deprecated clipops

needs this to land first
https://codereview.chromium.org/2877493002/#

Bug: skia:3191
Change-Id: Iff5271064877c4e96353d3564464f513eaad0bb5
Reviewed-on: https://skia-review.googlesource.com/16365
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/public.bzl b/public.bzl
index 1813af0..e798809 100644
--- a/public.bzl
+++ b/public.bzl
@@ -661,6 +661,7 @@
     # Staging flags for API changes
     # Temporarily Disable analytic AA for Google3
     "SK_NO_ANALYTIC_AA",
+    "SK_SUPPORT_DEPRECATED_CLIPOPS",
 ]
 
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