Fix: a number of unblock_points shouldn't unblock unconditionally

Initially diagnosed in an xnethack fuzzer crash - unblock_point
shouldn't be called when a closed door becomes non-closed, because it's
possible that there's a gas cloud on the space which means it still
blocks vision. These always need to be recalc_block_point. A number of
them were fixed, but when I went through all the xnethack ones, I found
some that were unchanged from upstream NetHack. I reproduced the sanity
check impossibles usually by breathing gas at a door as an iron golem
and then opening or destroying the door to trigger the unblock_point
call.

The use of recalc_block_point in wizterrainwish was not triggering this
bug, but the previous code there basically duplicated
recalc_block_point.

src/hack.c

@@ -787,7 +787,7 @@ still_chewing(coordxy x, coordxy y)
         lev->typ = CORR;
     }
 
-    unblock_point(x, y); /* vision */
+    recalc_block_point(x, y); /* vision */
     newsym(x, y);
     if (digtxt)
         You1(digtxt); /* after newsym */