patch 8.1.2422: "make depend" does not work correctly for libvterm

Problem:    "make depend" does not work correctly for libvterm.
Solution:   Fix build dependencies. And a few minor improvements.
diff --git a/src/version.c b/src/version.c
index 340867d..d9e47ac 100644
--- a/src/version.c
+++ b/src/version.c
@@ -743,6 +743,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2422,
+/**/
     2421,
 /**/
     2420,