Move stringpiece.h and stringprintf.h to base/.

Change-Id: I7f71b4a12f99c5f81771146c66629ae5a947b229
diff --git a/src/utils.h b/src/utils.h
index b73693c..40f0768 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -17,16 +17,17 @@
 #ifndef ART_SRC_UTILS_H_
 #define ART_SRC_UTILS_H_
 
-#include "base/logging.h"
-#include "globals.h"
-#include "primitive.h"
-#include "stringpiece.h"
-#include "stringprintf.h"
-
 #include <pthread.h>
+
 #include <string>
 #include <vector>
 
+#include "base/logging.h"
+#include "base/stringpiece.h"
+#include "base/stringprintf.h"
+#include "globals.h"
+#include "primitive.h"
+
 namespace art {
 
 class Class;