Use __rdtsc on Windows.

tools/Stats.h

 #ifndef Stats_DEFINED
 #define Stats_DEFINED
 
-#include <math.h>
-
 #include "SkString.h"
 #include "SkTSort.h"
 
 #ifdef SK_BUILD_FOR_WIN
     static const char* kBars[] = { ".", "o", "O" };
 #else
     static const char* kBars[] = { "▁", "▂", "▃", "▄", "▅", "▆", "▇", "█" };
 #endif
 
 struct Stats {
@@ skipping 27 matching lines @@
             if (min == max) {
                 // All samples are the same value.  Don't divide by zero.
                 plot.append(kBars[0]);
                 continue;
             }
 
             double s = samples[i];
             s -= min;
             s /= (max - min);
             s *= (SK_ARRAY_COUNT(kBars) - 1);
-            const size_t bar = (size_t)round(s);
+            const size_t bar = (size_t)(s + 0.5);
             SK_ALWAYSBREAK(bar < SK_ARRAY_COUNT(kBars));
             plot.append(kBars[bar]);
         }
     }
 
     double min;
     double max;
     double mean;    // Estimate of population mean.
     double var;     // Estimate of population variance.
     double median;
     SkString plot;  // A single-line bar chart (_not_ histogram) of the samples.
 };
 
 #endif//Stats_DEFINED