Fix text text changed events sending in OS X combo box and text control.

Fix text text changed events sending in OS X combo box and text control.

Don't duplicate needlessly wxTextEntry functionality in wxTextCtrl.

Don't clear the combobox text entry part twice in wxComboBox::DoClear(), it is
supposed to only clear the item container contents as the base class Clear()
already calls wxTextEntry::Clear().

Do send text updated events from wxTextEntry itself as it applies to
wxComboBox just as well as to wxTextCtrl.

The unit tests now pass under wxOSX/Cocoa, not breaking them again would be
appreciated.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63881 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775