Fix hero hiding under a statue shattered by land mine

Trigger a land mine while being polymorphed into a monster that
automatically hides (eg. scorpion). Have the statue on the land mine
shatter and all items on that square scatter away. Avoid falling
into the pit left by the land mine.

doc/fixes36.3

@@ -181,6 +181,7 @@ fix exploding land mine moving ball or chain and causing a sanity error
 fix firing attached iron ball when swallowed causing a sanity error
 fix vault guard impossible when he could not relocate in certain situation
 fix temple priests or shopkeepers moving over other monsters
+fix hero still hiding under a statue shattered by a land mine
 
 
 Fixes to Post-3.6.2 Problems that Were Exposed Via git Repository

src/explode.c

@@ -771,6 +771,9 @@ struct obj *obj; /* only scatter this obj        */
         newsym(x, y);
     }
     newsym(sx, sy);
+    if (sx == u.ux && sy == u.uy && u.uundetected
+        && hides_under(youmonst.data))
+        (void) hideunder(&youmonst);
     return total;
 }