updated for version 7.3.322
Problem:    #ifdef for PDP_RETVAL doesn't work, INT_PTR can be a typedef.
Solution:   Check the MSC version and 64 bit flags. (Sergiu Dotenco)
diff --git a/src/os_mswin.c b/src/os_mswin.c
index 49b1428..839c3df 100644
--- a/src/os_mswin.c
+++ b/src/os_mswin.c
@@ -1781,7 +1781,7 @@
 }
 
 /* Attempt to make this work for old and new compilers */
-#if !defined(_MSC_VER) || (_MSC_VER < 1300) || !defined(INT_PTR)
+#if !defined(_WIN64) && (!defined(_MSC_VER) || _MSC_VER < 1300)
 # define PDP_RETVAL BOOL
 #else
 # define PDP_RETVAL INT_PTR