Add oss-fuzz entrypoint for Polyutils fuzz

Bug: skia:
Change-Id: Iee7fe4344e65290ae25e4cd51f338d9ce56def55
Reviewed-on: https://skia-review.googlesource.com/c/161421
Reviewed-by: Kevin Lubick <kjlubick@google.com>

fuzz/oss_fuzz/FuzzPolyUtils.cpp

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2018 Google, LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "../Fuzz.h"
+
+void fuzz_PolyUtils(Fuzz* f);
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+    auto fuzz = Fuzz(SkData::MakeWithoutCopy(data, size));
+    fuzz_PolyUtils(&fuzz);
+    return 0;
+}