Fix Win64 compilation

dtool/src/parser-inc/iostream

@@ -47,15 +47,13 @@ __published:
 class ios : public ios_base {
 __published:
   typedef long fmtflags;
-#ifdef _WIN64
-  typedef unsigned __int64 streampos;
-  typedef __int64 streamoff;
-#elif defined(_WIN32)
-  typedef unsigned long streampos;
-  typedef long streamoff;
-#else
+#if defined(_WIN64) || !defined(_WIN32)
   typedef unsigned long long streampos;
   typedef long long streamoff;
+#else
+  // 32-bit Windows uses 32-bit stream offsets.
+  typedef unsigned long streampos;
+  typedef long streamoff;
 #endif
 
   bool good() const;