Add missing includes

This changes fixes "use of undeclared identifier 'INT_MAX'"
compilation error.

src/google/protobuf/io/coded_stream.h

@@ -110,6 +110,7 @@
 #define GOOGLE_PROTOBUF_IO_CODED_STREAM_H__
 
 #include <assert.h>
+#include <climits>
 #include <string>
 #include <utility>
 #ifdef _MSC_VER

src/google/protobuf/message_lite.h

@@ -39,6 +39,7 @@
 #ifndef GOOGLE_PROTOBUF_MESSAGE_LITE_H__
 #define GOOGLE_PROTOBUF_MESSAGE_LITE_H__
 
+#include <climits>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/stubs/logging.h>