Update posixmodule.c

Author: Wulian233

Modules/posixmodule.c

@@ -4189,8 +4189,8 @@ posix_getcwd(int use_bytes)
     /* If the buffer is large enough, len does not include the
        terminating \0. If the buffer is too small, len includes
        the space needed for the terminator. */
-    if ((size_t)len >= Py_ARRAY_LENGTH(wbuf)) {
-        if (len <= PY_SSIZE_T_MAX / sizeof(wchar_t)) {
+    if (len >= Py_ARRAY_LENGTH(wbuf)) {
+        if ((Py_ssize_t)len <= PY_SSIZE_T_MAX / sizeof(wchar_t)) {
             wbuf2 = PyMem_RawMalloc(len * sizeof(wchar_t));
         }
         else {