Fix an assortment of compiler warnings.

A few potential bugs were removed in the process.  Much code cleanup
remains to be done.

xrogue/potions.c

@@ -521,9 +521,10 @@ quaff(int which, int kind, int flags, bool is_potion)
                     fuse(sight, NULL, SEEDURATION, AFTER);
                     light(&hero);
                 }
-                else
+                else {
                     msg("The darkness around you thickens. ");
                     lengthen(sight, SEEDURATION);
+                }
             }
             else {
                 if (off(player, CANSEE)) {