wxMSW automatically extended wxTextCtrl length limit beyond the tiny standard
32KB when it was exceeded, but part of the text being appended into the
control was lost when doing it.
Fix this by retrying insertion after extending the limit.
Closes#15980.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75940 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775