Turn on library filter when library is selected.

It's a pretty good clue that the user wants to filter the footprints
by library (as it has no other purpose).

Fixes: lp:1780487
* https://bugs.launchpad.net/kicad/+bug/1780487

(cherry picked from commit b9a56f1)

cvpcb/library_listbox.cpp

@@ -211,6 +211,11 @@ void LIBRARY_LISTBOX::OnChar( wxKeyEvent& event )
 
 void LIBRARY_LISTBOX::OnSelectLibrary( wxListEvent& event )
 {
+    wxCommandEvent setLibraryFilterEvent;
+    setLibraryFilterEvent.SetId( ID_CVPCB_FOOTPRINT_DISPLAY_BY_LIBRARY_LIST );
+    setLibraryFilterEvent.SetInt( 1 );
+    GetParent()->OnSelectFilteringFootprint( setLibraryFilterEvent );
+
     SetFocus();
     GetParent()->OnSelectComponent( event );
 }