FIX: Fix imcludes for Python 3.6 on Windows

Fix inttype inclusion to enable building on Python 3.6/Windows

Author: bashtage

randomstate/interface/pcg-64/pcg-64-shim.h

@@ -1,5 +1,7 @@
 #ifdef _WIN32
-#include "../../src/common/inttypes.h"
+#ifndef _INTTYPES
+#include "../common/inttypes.h"
+#endif
 #define inline __forceinline
 #else
 #include <inttypes.h>

randomstate/src/pcg/pcg32.h

@@ -1,5 +1,7 @@
 #ifdef _WIN32
+#ifndef _INTTYPES
 #include "../common/inttypes.h"
+#endif
 #define inline __forceinline
 #else
 #include <inttypes.h>

randomstate/src/pcg64-compat/pcg64.h

@@ -26,7 +26,9 @@
 #define PCG64_H_INCLUDED 1
 
 #ifdef _WIN32
+#ifndef _INTTYPES
 #include "../common/inttypes.h"
+#endif
 #define inline __forceinline
 #else
 #include <inttypes.h>