[R] make all customizations to meet strict standard of cran

src/logging.cc

@@ -9,6 +9,8 @@
 #include "./common/sync.h"
 
 namespace xgboost {
+
+#if XGBOOST_CUSTOMIZE_LOGGER == 0
 ConsoleLogger::~ConsoleLogger() {
   std::cout << log_stream_.str() << std::endl;
 }
@@ -17,4 +19,5 @@ TrackerLogger::~TrackerLogger() {
   log_stream_ << '\n';
   rabit::TrackerPrint(log_stream_.str());
 }
+#endif
 }  // namespace xgboost