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/BigPathBench.cpp b/bench/BigPathBench.cpp
index a554b38..0ed8fc5 100644
--- a/bench/BigPathBench.cpp
+++ b/bench/BigPathBench.cpp
@@ -50,7 +50,7 @@
         make_path(fPath);
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         SkPaint paint;
         paint.setAntiAlias(true);
         paint.setStyle(SkPaint::kStroke_Style);