[#960] Fix logger warnings

sflphone-common/src/logger.cpp

@@ -87,12 +87,12 @@ void log(const int level, const char* format, ...)
 	message = buffer;
 	message = prefix + message;
 
-	syslog(level, message.c_str());
+	syslog(level, "%s", message.c_str());
 
 	if(consoleLog)
 	{
 		message = color_prefix + message + END_COLOR + "\n";
-		fprintf(stderr, message.c_str());
+		fprintf(stderr, "%s", message.c_str());
 	}
 }