patch 8.1.2038: has('vimscript-4') is always 0

Problem:    has('vimscript-4') is always 0.
Solution:   Add "vimscript-4" to the feature table. (Naruhiko Nishino,
            closes #4941)
diff --git a/src/version.c b/src/version.c
index 94ae34a..98e69d4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2038,
+/**/
     2037,
 /**/
     2036,