Eeschema: fix error in library pin table editor pin grouping broken in commit r5751.

* Coverity warns about falling through the switch statement which is acutally the correct behavior.

eeschema/dialogs/dialog_lib_edit_pin_table.cpp

@@ -526,7 +526,7 @@ void DIALOG_LIB_EDIT_PIN_TABLE::DataViewModel::Group::Add( Pin* aPin )
 
     case 1:
         m_Members.front()->SetGroup( this );
-        break;
+        // fall through
 
     default:
         aPin->SetGroup( this );