Flush out whatever the dialog-is-closing guard was for.

The guard isn't working on GTK (causing eval not to happen on
a kill focus), and I can't remember what issue I put it in to
solve.  I've done a bunch of testing and it appears that we
don't need it, although I'm sure I put it in for something....

Fixes: lp:1793911
* https://bugs.launchpad.net/kicad/+bug/1793911

common/widgets/unit_binder.cpp

@@ -94,10 +94,6 @@ void UNIT_BINDER::onSetFocus( wxFocusEvent& aEvent )
 
 void UNIT_BINDER::onKillFocus( wxFocusEvent& aEvent )
 {
-    // The ship is going down; no need to do anything...
-    if( !aEvent.GetWindow() || aEvent.GetWindow()->GetId() == wxID_CANCEL )
-        return;
-
     if( m_allowEval )
         evaluate();