Fix syntax error in interface headers

Although these headers are not supposed to be compiled, it's still
better to avoid at least the obvious typos in them.

Closes https://github.com/wxWidgets/wxWidgets/pull/2140

interface/wx/propgrid/editors.h

@@ -251,7 +251,7 @@ public:
 class wxPGChoiceEditor : public wxPGEditor
 {
 public:
-    wxPGChoiceEditor()
+    wxPGChoiceEditor();
     virtual ~wxPGChoiceEditor();
 
     virtual wxPGWindowList CreateControls(wxPropertyGrid* propgrid,