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

src/invent.c

@@ -4047,6 +4047,13 @@ display_inventory(const char *lets, boolean want_reply)
                            FALSE, want_reply, (long *) 0);
 }
 
+void
+repopulate_perminvent(void)
+{
+        (void) display_pickinv(NULL, (char *) 0, (char *) 0,
+                               FALSE, FALSE, (long *) 0);
+}
+
 /*
  * Show what is current using inventory letters.
  *