patch 8.1.1228: not possible to process tags with a function

Problem:    Not possible to process tags with a function.
Solution:   Add tagfunc() (Christian Brabandt, Andy Massimino, closes #4010)
diff --git a/src/normal.c b/src/normal.c
index 6b3a78b..e597e92 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -5724,7 +5724,11 @@
 	(void)normal_search(cap, cmdchar == '*' ? '/' : '?', buf, 0);
     }
     else
+    {
+	g_tag_at_cursor = TRUE;
 	do_cmdline_cmd(buf);
+	g_tag_at_cursor = FALSE;
+    }
 
     vim_free(buf);
 }