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)

Python/fileutils.c

@@ -2366,7 +2366,7 @@ _Py_dup(int fd)
         return -1;
     }
 
-#else
+#elif HAVE_DUP
     Py_BEGIN_ALLOW_THREADS
     _Py_BEGIN_SUPPRESS_IPH
     fd = dup(fd);
@@ -2383,6 +2383,10 @@ _Py_dup(int fd)
         _Py_END_SUPPRESS_IPH
         return -1;
     }
+#else
+    errno = ENOTSUP;
+    PyErr_SetFromErrno(PyExc_OSError);
+    return -1;
 #endif
     return fd;
 }