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/LineBench.cpp b/bench/LineBench.cpp
index 76231b8..67dc564 100644
--- a/bench/LineBench.cpp
+++ b/bench/LineBench.cpp
@@ -42,7 +42,7 @@
         return fName.c_str();
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         SkPaint paint;
         this->setupPaint(&paint);