gh-95174: Handle missing dup() and constants in WASI (GH-95229)

- check for ``dup()`` libc function
- handle missing ``F_DUPFD`` in ``dup2()`` replacement function
- add workaround for WASI libc bug in MSG_TRUNC
- ESHUTDOWN is missing, use EPIPE instead
- POLLPRI is missing, define as 0 (no-op)

PC/pyconfig.h

@@ -678,6 +678,9 @@ Py_NO_ENABLE_SHARED to find out.  Also support MS_NO_COREDLL for b/w compat */
 /* Define if you have the 'inet_pton' function. */
 #define HAVE_INET_PTON 1
 
+/* Define to 1 if you have the `dup' function. */
+#define HAVE_DUP 1
+
 /* framework name */
 #define _PYTHONFRAMEWORK ""