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/drawing.c

@@ -350,6 +350,14 @@ init_symbols()
 	init_r_symbols();
 }
 
+void
+update_bouldersym()
+{
+    showsyms[SYM_BOULDER + SYM_OFF_X] = iflags.bouldersym;
+    l_syms[SYM_BOULDER + SYM_OFF_X] = iflags.bouldersym;
+    r_syms[SYM_BOULDER + SYM_OFF_X] = iflags.bouldersym;
+}
+
 void
 init_showsyms()
 {

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;