patch 8.0.1399: warnings and errors when building tiny version

Problem:    Warnings and errors when building tiny version. (Tony Mechelynck)
Solution:   Add #ifdefs.
diff --git a/src/ops.c b/src/ops.c
index 1ecc677..cfa0bb3 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -1645,6 +1645,7 @@
     y_regs[1].y_array = NULL;		/* set register one to empty */
 }
 
+#ifdef FEAT_AUTOCMD
     static void
 yank_do_autocmd(oparg_T *oap, yankreg_T *reg)
 {
@@ -1701,6 +1702,7 @@
     dict_free_contents(v_event);
     hash_init(&v_event->dv_hashtab);
 }
+#endif
 
 /*
  * Handle a delete operation.