add index in getPixels for F16

src/core/SkLinearBitmapPipeline_sample.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLinearBitmapPipeline_sampler_DEFINED
 #define SkLinearBitmapPipeline_sampler_DEFINED
 
@@ skipping 759 matching lines @@
 
     void get4Pixels(const void* vsrc, int index, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) {
         const uint32_t* src = static_cast<const uint32_t*>(vsrc);
         *px0 = this->getPixelAt(src, index + 0);
         *px1 = this->getPixelAt(src, index + 1);
         *px2 = this->getPixelAt(src, index + 2);
         *px3 = this->getPixelAt(src, index + 3);
     }
 
     Sk4f getPixelAt(const void* vsrc, int index) {
-        const uint64_t* src = static_cast<const uint64_t*>(vsrc);
+        const uint64_t* src = static_cast<const uint64_t*>(vsrc) + index;
         return SkHalfToFloat_01(*src);
     }
 
     const void* row(int y) { return fSrc + y * fWidth[0]; }
 
 private:
     const uint64_t* const fSrc;
     const Sk4i            fWidth;
 };
 
 }  // namespace
 
 #endif  // SkLinearBitmapPipeline_sampler_DEFINED