Windows: fix unicode file path support

contrib/epee/src/file_io_utils.cpp

@@ -29,7 +29,7 @@
 #include <fstream>
 #include <boost/filesystem/path.hpp>
 #include <boost/filesystem/operations.hpp>
-#ifdef WIN32
+#ifdef _WIN32
 #include <windows.h>
 #include "string_tools.h"
 #endif
@@ -70,7 +70,7 @@ namespace file_io_utils
 
 	bool save_string_to_file(const std::string& path_to_file, const std::string& str)
 	{
-#ifdef WIN32
+#ifdef _WIN32
                 std::wstring wide_path;
                 try { wide_path = string_tools::utf8_to_utf16(path_to_file); } catch (...) { return false; }
                 HANDLE file_handle = CreateFileW(wide_path.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
@@ -104,7 +104,7 @@ namespace file_io_utils
 
 	bool load_file_to_string(const std::string& path_to_file, std::string& target_str, size_t max_size)
 	{
-#ifdef WIN32
+#ifdef _WIN32
                 std::wstring wide_path;
                 try { wide_path = string_tools::utf8_to_utf16(path_to_file); } catch (...) { return false; }
                 HANDLE file_handle = CreateFileW(wide_path.c_str(), GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
@@ -153,7 +153,7 @@ namespace file_io_utils
 
 	bool get_file_size(const std::string& path_to_file, uint64_t &size)
 	{
-#ifdef WIN32
+#ifdef _WIN32
                 std::wstring wide_path;
                 try { wide_path = string_tools::utf8_to_utf16(path_to_file); } catch (...) { return false; }
                 HANDLE file_handle = CreateFileW(wide_path.c_str(), GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);