alternative to display_inventory for window-port

Several window ports that support perm_invent were
using a call back to the core display_inventory()
function.

While calling from the window port back to core functions
is arguably not ideal in the first place, it was recently
brought to light that code NetHack-3.7 code changes to
display_inventory() actually caused it to stop repopulating
the perm_invent window as intended under certain circumstances.

For now, provide an alternative function, repopulate_perminvent(),
that hopefullshould still work the way it did previously.

There will likely be some additional changes after this to
further improve things, at some point.

For now though, this
Resolves #1454

win/Qt/qt_bind.cpp

@@ -502,7 +502,7 @@ void NetHackQtBind::qt_update_inventory(int arg UNUSED)
 
     /* doesn't work yet
     if (program_state.something_worth_saving && iflags.perm_invent)
-        display_inventory(NULL, false);
+        repopulate_perminvent();
     */
 }