more engraving sanity feedback

Delete engravings made in a breach of a shop's wall or of a vault's
wall or in the guard's temporary corridor when the wall is repaired
or the corridor removed.  If 'sanity_check' was On, those would
trigger impossible warning "engraving sanity: illegal surface (x)"
where x was the terrain type code for solid rock or relevant walls.

Adding del_engr_at() calls to the shop code was straightforward.
The vault code is very complicated and I'm not sure that all the
calls I added were actually necessary.

include/engrave.h

@@ -6,7 +6,12 @@
 #ifndef ENGRAVE_H
 #define ENGRAVE_H
 
-enum engraving_texts { actual_text, remembered_text, pristine_text, text_states };
+enum engraving_texts {
+    actual_text,
+    remembered_text,
+    pristine_text,
+    text_states
+};
 
 struct engr {
     struct engr *nxt_engr;
@@ -37,9 +42,9 @@ struct engr {
 #define dealloc_engr(engr) free((genericptr_t) (engr))
 
 #define engraving_to_defsym(ep) \
-    (levl[(ep)->engr_x][(ep)->engr_y].typ == CORR ? S_engrcorr : S_engroom)
+    ((levl[(ep)->engr_x][(ep)->engr_y].typ == CORR) ? S_engrcorr : S_engroom)
 
-#define spot_shows_engravings(x,y)      \
+#define spot_shows_engravings(x,y) \
     (levl[(x)][(y)].typ == CORR         \
      || levl[(x)][(y)].typ == SCORR     \
      || levl[(x)][(y)].typ == ICE       \