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/BlurRoundRectBench.cpp b/bench/BlurRoundRectBench.cpp
index 9f1e143..5213276 100644
--- a/bench/BlurRoundRectBench.cpp
+++ b/bench/BlurRoundRectBench.cpp
@@ -39,7 +39,7 @@
                               SkScalarCeilToInt(fRRect.rect().height()));
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         SkLayerDrawLooper::Builder looperBuilder;
         {
             SkLayerDrawLooper::LayerInfo info;