toggling persistent inventory window

Something else noticed while testing #H8271:  toggling perm_invent on
with 'O' didn't show anything (at least with curses) until some later
action caused it to be updated.  Make updating persistent inventory be
included with full redraw and set the need_redraw flag when toggling
perm_invent.

src/display.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	display.c	$NHDT-Date: 1540502147 2018/10/25 21:15:47 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.94 $ */
+/* NetHack 3.6	display.c	$NHDT-Date: 1551138503 2019/02/25 23:48:23 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.97 $ */
 /* Copyright (c) Dean Luick, with acknowledgements to Kevin Darcy */
 /* and Dave Cohrs, 1990.                                          */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -1374,6 +1374,9 @@ docrt()
     /* overlay with monsters */
     see_monsters();
 
+    /* perm_invent */
+    update_inventory();
+
     context.botlx = 1; /* force a redraw of the bottom line */
 }