Treat G_IO_HUP as read, not error, event because EOF is not exceptional.

Treat G_IO_HUP as read, not error, event because EOF is not exceptional.

When EOF is reached on a file descriptor, call the handler OnReadWaiting()
because this is not really different from getting to the EOF while reading
data in the same function. Only call OnExceptionWaiting() for the real errors.

See #10258.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74348 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775