Fix compile failure after rIfe1dc0791040150132bea6884f1e6c8d31972d1b

Bug: 23290056
Change-Id: If6e22b0159de6635a8ca5305895b7718f15becc7

libutils/String8.cpp

diff --git a/libutils/String8.cpp b/libutils/String8.cpp
index e5a48e5..bb06825 100644
--- a/libutils/String8.cpp
+++ b/libutils/String8.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#define __STDC_LIMIT_MACROS
+#include <stdint.h>
+
 #include <utils/String8.h>
 
 #include <utils/Log.h>