Issue #21151: Fixed a segfault in the _winreg module.

When ``None`` was passed as a ``REG_BINARY`` value to SetValueEx,
PyMem_DEL was called on an uninitialized buffer.  Patch by John Ehresman.

(Also an incidental typo fix in a comment in test_winreg)
diff --git a/Misc/NEWS b/Misc/NEWS
index 6f266ab..4384562 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -13,6 +13,9 @@
 Library
 -------
 
+- Issue #21151: Fixed a segfault in the _winreg module when ``None`` is passed
+  as a ``REG_BINARY`` value to SetValueEx.  Patch by John Ehresman.
+
 - Issue #21090: io.FileIO.readall() does not ignore I/O errors anymore. Before,
   it ignored I/O errors if at least the first C call read() succeed.