COMPMID-2177 Fix clang warnings

Change-Id: I4beacfd714ee3ed771fd174cce5d8009a2961380
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/1065
Reviewed-by: Giuseppe Rossini <giuseppe.rossini@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/utils/logging/LoggerRegistry.cpp b/src/core/utils/logging/LoggerRegistry.cpp
index 99236d2..3a46696 100644
--- a/src/core/utils/logging/LoggerRegistry.cpp
+++ b/src/core/utils/logging/LoggerRegistry.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 ARM Limited.
+ * Copyright (c) 2017-2019 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -66,7 +66,7 @@
     return (_loggers.find(name) != _loggers.end()) ? _loggers[name] : nullptr;
 }
 
-void LoggerRegistry::create_reserved_loggers(LogLevel log_level, std::vector<std::shared_ptr<Printer>> printers)
+void LoggerRegistry::create_reserved_loggers(LogLevel log_level, const std::vector<std::shared_ptr<Printer>> &printers)
 {
     std::lock_guard<arm_compute::Mutex> lock(_mtx);
     for(const auto &r : _reserved_loggers)