updates for MSVC 2015's degenerate headers

Note that 'perror' moves from stdio.h to stdlib.h, and 'rename' moves
from stdio.h to io.h. Also, standard C includes move from the compiler
to the Windows SDK, which changes the base path for the include files.

include/compat/sys/stat.h

@@ -11,7 +11,11 @@
 #else
 
 #include <windows.h>
+#if _MSC_VER >= 1900
+#include <../ucrt/sys/stat.h>
+#else
 #include <../include/sys/stat.h>
+#endif
 
 /* File type and permission flags for stat() */
 #if !defined(S_IFMT)

include/compat/sys/types.h

@@ -4,7 +4,11 @@
  */
 
 #ifdef _MSC_VER
+#if _MSC_VER >= 1900
+#include <../ucrt/sys/types.h>
+#else
 #include <../include/sys/types.h>
+#endif
 #else
 #include_next <sys/types.h>
 #endif