patch 8.1.1526: no numerical value for the patchlevel

Problem:    No numerical value for the patchlevel.
Solution:   Add v:versionlong.
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index db68e2a..08ab59e 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -171,6 +171,9 @@
   echo version
   call assert_fails('let version = 1', 'E46:')
   call assert_equal(v:version, version)
+
+  call assert_equal(v:version, v:versionlong / 10000)
+  call assert_true(v:versionlong > 8011525)
 endfunc
 
 func Test_scriptversion()