Windows support for HASHFileChunk()

<io.h> provides the necessary file I/O functions.

[guillem@hadrons.org: Move include before <hashinc>. ]
Signed-off-by: Guillem Jover <guillem@hadrons.org>

src/hash/helper.c

@@ -19,6 +19,9 @@
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
+#ifdef _WIN32
+#include <io.h>
+#endif
 
 #include <hashinc>