vim-patch:9.1.0546: vim-tiny fails on CTRL-X/CTRL-A

Problem:  vim-tiny fails on CTRL-X/CTRL-A
          (Rob Foehl, after 9.1.0172)
Solution: Move #ifdefs, so that after changing the line in del_bytes,
          the cached textlen value is invalidated

closes: vim/vim#15178

03acd4761b

Co-authored-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>

test/functional/legacy/028_source_ctrl_v_spec.lua

@@ -5,10 +5,10 @@ local n = require('test.functional.testnvim')()
 local clear, feed, insert = n.clear, n.feed, n.insert
 local feed_command, expect = n.feed_command, n.expect
 
-describe('CTRL-V at the end of the line', function()
-  setup(clear)
+describe('028', function()
+  before_each(clear)
 
-  it('is working', function()
+  it('CTRL-V at the end of the line is working', function()
     insert([[
       firstline
       map __1 afirst
@@ -35,6 +35,21 @@ describe('CTRL-V at the end of the line', function()
       map __2 asdsecondsdsd0map __5 asd0fifth]])
   end)
 
+  it('CTRL-X/CTRL-A is working', function()
+    insert([[
+      12352
+
+      12354]])
+    feed_command('/12352')
+    feed('<C-A>')
+    feed_command('/12354')
+    feed('<C-X>')
+    expect([[
+      12353
+
+      12353]])
+  end)
+
   teardown(function()
     os.remove('Xtestfile')
   end)