Can't build with VS2012

[garick2die4]

I've trying to build libxdiff in Windows. But my build fails because there is no unistd.h file:
d:\kovia\projects\libxdiff\xinclude.h(31) : fatal error C1083: Cannot open inclu
de file: 'unistd.h': No such file or directory
NMAKE : fatal error U1077: '"C:\Program Files (x86)\Microsoft Visual Studio 11.0
\VC\BIN\cl.exe"' : return code '0x2'
Stop.

I found the following code in xinclude.h from libgit2:
It seems that this change solves the problem:

ifdef _WIN32

else

include <unistd.h>

endif

Could you please fix it in master?