Allow changing alignment styles after wxTextCtrl creation (wxOSX)

Update NSTextView/NSTextField alignment mode when wxTextCtrl alignment styles are changed with SetWindowStyleFlag().

Closes #17952.

include/wx/osx/textctrl.h

@@ -100,6 +100,7 @@ public:
     virtual void Command(wxCommandEvent& event) wxOVERRIDE;
 
     virtual bool AcceptsFocus() const wxOVERRIDE;
+    virtual void SetWindowStyleFlag(long style) wxOVERRIDE;
 
     // callbacks
     void OnDropFiles(wxDropFilesEvent& event);