MSVC: xz: Use _isatty() from <io.h> to implement isatty().

src/xz/message.c

@@ -15,6 +15,11 @@
 
 #include <stdarg.h>
 
+#ifdef _MSC_VER
+#	include <io.h>
+#	define isatty _isatty
+#endif
+
 
 /// Number of the current file
 static unsigned int files_pos = 0;

src/xz/util.c

@@ -13,6 +13,11 @@
 #include "private.h"
 #include <stdarg.h>
 
+#ifdef _MSC_VER
+#	include <io.h>
+#	define isatty _isatty
+#endif
+
 
 /// Buffers for uint64_to_str() and uint64_to_nicestr()
 static char bufs[4][128];