add more SK_WARN_UNUSED_RESULT attributes to functions that ignore out-params if they fail

src/core/SkCubicClipper.h

 /*
  * Copyright 2009 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkCubicClipper_DEFINED
 #define SkCubicClipper_DEFINED
 
 #include "SkPoint.h"
 #include "SkRect.h"
 
 /** This class is initialized with a clip rectangle, and then can be fed cubics,
     which must already be monotonic in Y.
 
     In the future, it might return a series of segments, allowing it to clip
     also in X, to ensure that all segments fit in a finite coordinate system.
  */
 class SkCubicClipper {
 public:
     SkCubicClipper();
 
     void setClip(const SkIRect& clip);
 
-    bool clipCubic(const SkPoint src[4], SkPoint dst[4]);
+    bool SK_WARN_UNUSED_RESULT clipCubic(const SkPoint src[4], SkPoint dst[4]);
 
-    static bool ChopMonoAtY(const SkPoint pts[4], SkScalar y, SkScalar* t);
+    static bool SK_WARN_UNUSED_RESULT ChopMonoAtY(const SkPoint pts[4], SkScalar y, SkScalar* t);
 private:
     SkRect      fClip;
 };
 
 #endif  // SkCubicClipper_DEFINED