win32: fix close and improve cancel (no error when write is canceled)
diff --git a/serial/win32.py b/serial/win32.py
index 2fddf6b..31f21ee 100644
--- a/serial/win32.py
+++ b/serial/win32.py
@@ -219,6 +219,7 @@
 MAXDWORD = 4294967295  # Variable c_uint
 EV_RLSD = 32  # Variable c_int
 ERROR_SUCCESS = 0
+ERROR_OPERATION_ABORTED = 995
 ERROR_IO_INCOMPLETE = 996
 ERROR_IO_PENDING = 997  # Variable c_long
 MS_CTS_ON = 16  # Variable c_ulong