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/ScalarBench.cpp b/bench/ScalarBench.cpp
index 2c59fa5..0048c6e 100644
--- a/bench/ScalarBench.cpp
+++ b/bench/ScalarBench.cpp
@@ -31,7 +31,7 @@
         return fName.c_str();
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         for (int i = 0; i < loops; i++) {
             this->performTest();
         }
@@ -149,7 +149,7 @@
         return "rect_bounds";
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         SkRect r;
         for (int i = 0; i < loops; ++i) {
             for (int i = 0; i < 1000; ++i) {