Issue #17968: Fix memory leak in os.listxattr().

diff --cc Misc/NEWS
Simple merge

diff --cc Modules/posixmodule.c
index 1149856e3055db01103d5ec61cd535d97936e027,3e5e58045fdcd0fd5f22c27742d4cfc945389281..8e84392d5ca85e1a4d6b745304bc0cbc7d427317
--- 1/Modules/posixmodule.c
--- 2/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@@ -10119,9 -10625,11 +10119,11 @@@ posix_listxattr(PyObject *self, PyObjec
          Py_END_ALLOW_THREADS;
  
          if (length < 0) {
-             if (errno == ERANGE)
+             if (errno == ERANGE) {
+                 PyMem_FREE(buffer);
                  continue;
 -            path_error("listxattr", &path);
+             }
 +            path_error(&path);
              break;
          }