Add SK_SUPPORT_LEGACY_ACCESSBITMAP to public.bzl.

BUG=skia:
TBR=robertphillips
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2165633008

Review-Url: https://codereview.chromium.org/2165633008
diff --git a/public.bzl b/public.bzl
index 13f89b3..73a217e 100644
--- a/public.bzl
+++ b/public.bzl
@@ -588,17 +588,18 @@
     # Turn on a few Google3-specific build fixes.
     "GOOGLE3",
     # Staging flags for API changes
+    "SK_SUPPORT_LEGACY_ACCESSBITMAP",
     "SK_SUPPORT_LEGACY_COLORFILTER_PTR",
     "SK_SUPPORT_LEGACY_CREATESHADER_PTR",
+    "SK_SUPPORT_LEGACY_IMAGEFACTORY",
     "SK_SUPPORT_LEGACY_IMAGEFILTER_PTR",
+    "SK_SUPPORT_LEGACY_MASKFILTER_PTR",
     "SK_SUPPORT_LEGACY_MINOR_EFFECT_PTR",
     "SK_SUPPORT_LEGACY_NEW_SURFACE_API",
     "SK_SUPPORT_LEGACY_PATHEFFECT_PTR",
     "SK_SUPPORT_LEGACY_PICTURE_PTR",
-    "SK_SUPPORT_LEGACY_MASKFILTER_PTR",
-    "SK_SUPPORT_LEGACY_IMAGEFACTORY",
-    "SK_SUPPORT_LEGACY_XFERMODE_PTR",
     "SK_SUPPORT_LEGACY_TYPEFACE_PTR",
+    "SK_SUPPORT_LEGACY_XFERMODE_PTR",
 ]
 
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