Fix compilation on Windows

[pierotofy]

Hello ✋

Trying to compile Untwine on Windows (Windows 10, Visual Studio 2019) I get the following:

  Untwine.cpp
D:\ddb\untwine\untwine\MapFile.cpp(50,18): error C2039: '_open': is not a member of '`global namespace'' [D:\ddb\untwin
e\build\untwine.vcxproj]
D:\ddb\untwine\untwine\MapFile.cpp(50,53): error C2065: '_O_RDONLY': undeclared identifier [D:\ddb\untwine\build\untwin
e.vcxproj]
D:\ddb\untwine\untwine\MapFile.cpp(50,65): error C2065: '_O_RDWR': undeclared identifier [D:\ddb\untwine\build\untwine.
vcxproj]
D:\ddb\untwine\untwine\MapFile.cpp(50,23): error C3861: '_open': identifier not found [D:\ddb\untwine\build\untwine.vcx
proj]
D:\ddb\untwine\untwine\MapFile.cpp(68,46): error C3861: '_get_osfhandle': identifier not found [D:\ddb\untwine\build\un
twine.vcxproj]
D:\ddb\untwine\untwine\MapFile.cpp(103,7): error C2039: '_close': is not a member of '`global namespace'' [D:\ddb\untwi
ne\build\untwine.vcxproj]
D:\ddb\untwine\untwine\MapFile.cpp(103,13): error C3861: '_close': identifier not found [D:\ddb\untwine\build\untwine.v
cxproj]
D:\ddb\untwine\epf\FileProcessor.cpp(77,1): error C3493: 'CountIncrement' cannot be implicitly captured because no defa
ult capture mode has been specified [D:\ddb\untwine\build\untwine.vcxproj]

So I did the following:

• Include fcntl.h and io.h which on Windows provide the functions / constants being reported as missing.
• Set a capture mode for CountIncrement.

Let me know if changes are needed.

[abellgithub]

Thanks. I'll verify. Maybe I'll have time to set up some CI.

[hobu]

Confirmed this fixes for me on 2017.