Eeschema: fix broken symbol library links after sheet edit.

Refresh the currently edit sheet screen symbol links when the sheet file
name is changed.

https://bugs.launchpad.net/kicad/+bug/1830315

Fixes lp:1830315

eeschema/sheet.cpp

@@ -253,6 +253,11 @@ bool SCH_EDIT_FRAME::EditSheet( SCH_SHEET* aSheet, SCH_SHEET_PATH* aHierarchy,
 
             return false;
         }
+
+        SCH_SCREEN* screen = aSheet->GetScreen();
+
+        if( screen )
+            screen->UpdateSymbolLinks( true );
     }
 
     aSheet->SetFileNameSize( dlg.GetFileNameTextSize() );