Fix run-test on host.

Change-Id: I44ebb4cdc2f5966be51a063e3c7256ab3016c404
diff --git a/src/runtime.cc b/src/runtime.cc
index 12f7c8b..014ce6b 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -22,6 +22,7 @@
 #include <cstdlib>
 #include <limits>
 #include <vector>
+#include <fstream>
 
 #include "class_linker.h"
 #include "class_loader.h"
@@ -421,6 +422,15 @@
           gLogVerbosity.third_party_jni = true;
         } else if (verbose_options[i] == "threads") {
           gLogVerbosity.threads = true;
+        } else if (StartsWith(verbose_options[i], "log-to=")) {
+          std::string log_file_name(verbose_options[i].substr(strlen("log-to=")));
+          std::ofstream* log_file = new std::ofstream(log_file_name.c_str());
+          if (log_file->is_open() && log_file->good()) {
+            gLogVerbosity.SetLoggingStream(log_file);
+          } else {
+            LOG(ERROR) << "Fail to open log file: \"" << log_file_name << "\","
+                       << " use default logging stream.";
+          }
         } else {
           LOG(WARNING) << "Ignoring unknown -verbose option: " << verbose_options[i];
         }