This might be less consistent with the other selection modes but seems to be
more convenient in practice, so restore the old, 2.8 behaviour and select the
entire row/column on a simply click in row/column selection mode.
Closes#12062.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64383 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775