Map ERROR_NETNAME_DELETED to canceled in make_err

IOCP delivers ERROR_NETNAME_DELETED (64) when closesocket()
cancels pending overlapped I/O, despite MSDN documenting
ERROR_OPERATION_ABORTED for that case. This became visible
after SO_UPDATE_CONNECT_CONTEXT was added to ConnectEx sockets,
which caused TLS shutdown tests to receive unmapped error 64.

Author: sgerbino

include/boost/corosio/detail/make_err.hpp

@@ -52,9 +52,14 @@ make_err(int errn) noexcept
 
 /** Convert a Windows error code to std::error_code.
 
-    Maps ERROR_OPERATION_ABORTED and ERROR_CANCELLED to capy::error::canceled.
+    Maps ERROR_OPERATION_ABORTED, ERROR_CANCELLED, and
+    ERROR_NETNAME_DELETED to capy::error::canceled.
     Maps ERROR_HANDLE_EOF to capy::error::eof.
 
+    ERROR_NETNAME_DELETED (64) is what IOCP actually delivers
+    when closesocket() cancels pending overlapped I/O, despite
+    MSDN documenting ERROR_OPERATION_ABORTED for that case.
+
     @param dwError The Windows error code (DWORD).
     @return The corresponding std::error_code.
 */
@@ -64,7 +69,8 @@ make_err(unsigned long dwError) noexcept
     if (dwError == 0)
         return {};
 
-    if (dwError == ERROR_OPERATION_ABORTED || dwError == ERROR_CANCELLED)
+    if (dwError == ERROR_OPERATION_ABORTED || dwError == ERROR_CANCELLED ||
+        dwError == ERROR_NETNAME_DELETED)
         return capy::error::canceled;
 
     if (dwError == ERROR_HANDLE_EOF)