patch 8.2.2675: directory change in a terminal window shell is not followed

Problem:    Directory change in a terminal window shell is not followed.
Solution:   Add the 'autoshelldir' option. (closes #6290)
diff --git a/src/feature.h b/src/feature.h
index 5f6f800..4df73d1 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -1148,6 +1148,12 @@
 #endif
 
 /*
+ * +autoshelldir	    'autoshelldir' option.
+ */
+#if defined(FEAT_TERMINAL)
+# define FEAT_AUTOSHELLDIR
+#endif
+/*
  * +textprop and +popupwin	Text PROPerties and POPUP windows
  */
 #if defined(FEAT_EVAL) && defined(FEAT_SYN_HL)