Move Stopwatch into its own header

Bug: 29748723
Test: netd_integration_test

(cherry picked from commit cc544162e08dd0df271cd77a3f2c85dbaaa461e2)

Change-Id: I02a9ad8591d1c98f146fe2fe8c3b25a2d752ab55
diff --git a/tests/binder_test.cpp b/tests/binder_test.cpp
index 9638230..5f60642 100644
--- a/tests/binder_test.cpp
+++ b/tests/binder_test.cpp
@@ -42,6 +42,7 @@
 #include <netutils/ifc.h>
 
 #include "NetdConstants.h"
+#include "Stopwatch.h"
 #include "android/net/INetd.h"
 #include "android/net/UidRange.h"
 #include "binder/IServiceManager.h"