move to CXX Flags to prevent warning by compiling c code, adding include for unix

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.0)
 project(Gradido_LoginServer C CXX)
 SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY "bin" )
 
-add_definitions("-std=c++11")
+SET ( CMAKE_CXX_FLAGS "-std=c++17" )
 
 include_directories(
 	"dependencies" 

src/cpp/lib/DataTypeConverter.cpp

@@ -3,6 +3,9 @@
 #include <stdexcept>
 #include "sodium.h"
 
+// needed for memset in linux
+#include <string.h>
+
 namespace DataTypeConverter
 {
 	NumberParseState strToInt(const std::string& input, int& result)

src/cpp/lib/DataTypeConverter.h

@@ -4,6 +4,7 @@
 #include <string>
 #include "../SingletonManager/MemoryManager.h"
 
+
 namespace DataTypeConverter {
 
 	enum NumberParseState