Fix Windows build.

llvm-svn: 239279

llvm/lib/Object/ArchiveWriter.cpp

@@ -24,7 +24,11 @@
 #include "llvm/Support/ToolOutputFile.h"
 #include "llvm/Support/raw_ostream.h"
 
+#if !defined(_MSC_VER) && !defined(__MINGW32__)
 #include <unistd.h>
+#else
+#include <io.h>
+#endif
 
 using namespace llvm;