dex2oat: Avoid extra std::string copy

The function Fatal() takes a const std::string reference, so it's
inefficient to pass it std::string::c_str().  While it's not
useful optimize a fatal code path, we still fix this so static
analysis tools finding this issue in other parts of the code
are less noisy.

Test: TreeHugger
Change-Id: I42231b40c1af2f866c451e169f2d8362154853b0
diff --git a/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index 0859a43..b44dc3f 100644
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -619,7 +619,7 @@
                            timeout_in_milliseconds_/1000));
       } else if (rc != 0) {
         std::string message(StringPrintf("pthread_cond_timedwait failed: %s", strerror(rc)));
-        Fatal(message.c_str());
+        Fatal(message);
       }
     }
     CHECK_WATCH_DOG_PTHREAD_CALL(pthread_mutex_unlock, (&mutex_), reason);