Make nanobench --outResultsFile only work with Release builds.

bench/nanobench.cpp

Index: bench/nanobench.cpp
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 7efd858c5cd5a8a0e761c399a839fa6964526e2b..0a8e7355a27e7f549537630038b5d433c2be1c53 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -1054,7 +1054,12 @@ int nanobench_main() {
 
     SkAutoTDelete<ResultsWriter> log(new ResultsWriter);
     if (!FLAGS_outResultsFile.isEmpty()) {
+#if defined(SK_RELEASE)
         log.reset(new NanoJSONResultsWriter(FLAGS_outResultsFile[0]));
+#else
+        SkDebugf("I'm ignoring --outResultsFile because this is a Debug build.");
+        return 1;
+#endif
     }
 
     if (1 == FLAGS_properties.count() % 2) {