Remove const from `const int loops`.

This drives me nuts, and prevents `while (loops --> 0)`.

BUG=skia:

Review URL: https://codereview.chromium.org/1379923005
diff --git a/bench/PerlinNoiseBench.cpp b/bench/PerlinNoiseBench.cpp
index 3fbb723..7c4894d 100644
--- a/bench/PerlinNoiseBench.cpp
+++ b/bench/PerlinNoiseBench.cpp
@@ -21,7 +21,7 @@
         return "perlinnoise";
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         this->test(loops, canvas, 0, 0, SkPerlinNoiseShader::kFractalNoise_Type,
                    0.1f, 0.1f, 3, 0, false);
     }
@@ -38,7 +38,7 @@
         canvas->restore();
     }
 
-    void test(const int loops, SkCanvas* canvas, int x, int y, SkPerlinNoiseShader::Type type,
+    void test(int loops, SkCanvas* canvas, int x, int y, SkPerlinNoiseShader::Type type,
               float baseFrequencyX, float baseFrequencyY, int numOctaves, float seed,
               bool stitchTiles) {
         SkShader* shader = (type == SkPerlinNoiseShader::kFractalNoise_Type) ?