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/CmapBench.cpp b/bench/CmapBench.cpp
index 5bec506..a2fb506 100644
--- a/bench/CmapBench.cpp
+++ b/bench/CmapBench.cpp
@@ -85,7 +85,7 @@
         return fName.c_str();
     }
 
-    void onDraw(const int loops, SkCanvas* canvas) override {
+    void onDraw(int loops, SkCanvas* canvas) override {
         fProc(loops, fPaint, fText, sizeof(fText), NGLYPHS);
     }