patch 8.0.1647: terminal API may call any user function

Problem:    Terminal API may call a function not meant to be called by this
            API.
Solution:   Require the function to start with Tapi_.
diff --git a/src/version.c b/src/version.c
index 14bf136..df56277 100644
--- a/src/version.c
+++ b/src/version.c
@@ -767,6 +767,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1647,
+/**/
     1646,
 /**/
     1645,