Handle boulder-option in config file

Setting boulder in config file did not work correctly in post-3.4.3
code, due to the symset changes.

src/options.c

@@ -744,6 +744,8 @@ initoptions_finish()
 	/* result in the player's preferred fruit [better than "\033"].	*/
 	obj_descr[SLIME_MOLD].oc_name = "fruit";
 
+        if (iflags.bouldersym) update_bouldersym();
+
 	reglyph_darkroom();
 
 	return;