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/evalfunc.c b/src/evalfunc.c
index 6772692..b352ea9 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -3771,6 +3771,7 @@
 	"vimscript-1",
 	"vimscript-2",
 	"vimscript-3",
+	"vimscript-4",
 	"virtualedit",
 	"visual",
 	"visualextra",
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index 720f309..4e8b782 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -194,6 +194,7 @@
 
 scriptversion 4
 func Test_vvar_scriptversion4()
+  call assert_true(has('vimscript-4'))
   call assert_equal(17, 017)
   call assert_equal(18, 018)
   call assert_equal(64, 0b1'00'00'00)
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,