Issue #40: Repara a falta de #pragma once nos .h

Signed-off-by: Felipe Wu <fsiw15@inf.ufpr.br>

include/agent/linux/get_disks_info.h

+#pragma once
 struct disk {
     std::string model;
     long long size;

include/agent/windows/get_macaddr.h

+#pragma once
 #include <stdio.h>
 #include <Windows.h>
 #include <Iphlpapi.h>

include/agent/windows/get_machine_type.h

+#pragma once
 #define _WIN32_WINNT 0x0500
 #include <windows.h>
 #include <stdio.h>