Add base types for path ops

src/pathops/SkPathOpsPoint.cpp

Index: src/pathops/SkPathOpsPoint.cpp
===================================================================
--- src/pathops/SkPathOpsPoint.cpp	(revision 0)
+++ src/pathops/SkPathOpsPoint.cpp	(revision 0)
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SkPathOpsPoint.h"
+
+SkDVector operator-(const SkDPoint& a, const SkDPoint& b) {
+    SkDVector v = {a.fX - b.fX, a.fY - b.fY};
+    return v;
+}
+
+SkDPoint operator+(const SkDPoint& a, const SkDVector& b) {
+    SkDPoint v = {a.fX + b.fX, a.fY + b.fY};
+    return v;
+}