add flag to stage removing deprecated skia api

Change-Id: Ia2e059473343a5672df601ff3c56b1fb3e6ebf17
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1946684
Commit-Queue: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720544}

skia/config/SkUserConfig.h

@@ -211,6 +211,10 @@ SK_API void SkDebugf_FileLine(const char* file,
 #define SK_DISABLE_REDUCE_OPLIST_SPLITTING
 #endif
 
+#ifndef SK_SUPPORT_LEGACY_PATHITER_NEXT
+#define SK_SUPPORT_LEGACY_PATHITER_NEXT
+#endif
+
 #ifndef SK_IGNORE_LINEONLY_AA_CONVEX_PATH_OPTS
 #define SK_IGNORE_LINEONLY_AA_CONVEX_PATH_OPTS
 #endif