Update incremental dexing benchmark to follow our normal output style

R=ager@google.com

Bug:
Change-Id: I38639856c8bd22de570651f87faedc32b3e46830

src/main/java/com/android/tools/r8/IncrementalDexingBenchmark.java

diff --git a/src/main/java/com/android/tools/r8/IncrementalDexingBenchmark.java b/src/main/java/com/android/tools/r8/IncrementalDexingBenchmark.java
index 7b9d8aa..e509bf1 100644
--- a/src/main/java/com/android/tools/r8/IncrementalDexingBenchmark.java
+++ b/src/main/java/com/android/tools/r8/IncrementalDexingBenchmark.java
@@ -33,7 +33,7 @@
         compile(executor);
       }
       double elapsedMs = (System.nanoTime() - start) / 1000000.0;
-      System.out.println("Runtime: " + elapsedMs + " ms");
+      System.out.println("IncrementalDexing(Runtime): " + elapsedMs + " ms");
     } finally {
       executor.shutdown();
     }