patch 8.2.5081: autocmd test fails on MS-Windows

Problem:    Autocmd test fails on MS-Windows.
Solution:   Set shellslash to get forward slashes.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 15aab48..d0b5b5a 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -2108,12 +2108,15 @@
   exe 'lcd ' .. fnameescape(s:dir_bar)
   call assert_equal(expected, s:li)
 
+  let save_shellslash = &shellslash
+  set shellslash
   exe 'cd ' .. s:dir_foo
   exe 'cd ' .. s:dir_bar
   autocmd! test_dirchanged DirChanged global let g:result = expand("<afile>")
   cd -
   call assert_equal(s:dir_foo, g:result)
 
+  let &shellslash = save_shellslash
   call s:After_test_dirchanged()
 endfunc
 
diff --git a/src/version.c b/src/version.c
index 20ca4eb..117a432 100644
--- a/src/version.c
+++ b/src/version.c
@@ -735,6 +735,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    5081,
+/**/
     5080,
 /**/
     5079,