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/TextBlobBench.cpp b/bench/TextBlobBench.cpp
index 5f4dbba..6d5a88f 100644
--- a/bench/TextBlobBench.cpp
+++ b/bench/TextBlobBench.cpp
@@ -54,7 +54,7 @@
         return "TextBlobBench";
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         SkPaint paint;
 
         // To ensure maximum caching, we just redraw the blob at the same place everytime