Fix VS 2015 build

tools/sk_tool_utils.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "sk_tool_utils.h"
 #include "sk_tool_utils_flags.h"
 
@@ skipping 216 matching lines @@
 
     for (int y = dst.fTop; y < dst.fBottom; ++y) {
         for (int x = dst.fLeft; x < dst.fRight; ++x) {
             norm.fX = (x + 0.5f - center.fX) / halfSize.fX;
             norm.fY = (y + 0.5f - center.fY) / halfSize.fY;
             
             SkScalar tmp = norm.fX * norm.fX + norm.fY * norm.fY;
             if (tmp >= 1.0f) {
                 norm.set(0.0f, 0.0f, 1.0f);
             } else {
-                norm.fZ = sqrt(1.0f - tmp);
+                norm.fZ = sqrtf(1.0f - tmp);
             }
 
             norm_to_rgb(bm, x, y, norm);
         }
     }
 }
 
 void create_frustum_normal_map(SkBitmap* bm, const SkIRect& dst) {
     const SkPoint center = SkPoint::Make(dst.fLeft + (dst.width() / 2.0f),
                                          dst.fTop + (dst.height() / 2.0f));
@@ skipping 64 matching lines @@
                     norm = leftUp;
                 }    
             }
 
             norm_to_rgb(bm, x, y, norm);
         }
     }
 }
 
 }  // namespace sk_tool_utils