patch 8.2.3780: ":cd" works differently on MS-Windows

Problem:    ":cd" works differently on MS-Windows.
Solution:   Add the 'cdhome' option. (closes #9324)
diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 1b826c7..38bc87e 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -260,6 +260,10 @@
 call <SID>AddOption("path", gettext("list of directory names used for file searching"))
 call append("$", "\t" .. s:global_or_local)
 call <SID>OptionG("pa", &pa)
+if exists("+cdhome")
+  call <SID>AddOption("cdhome", gettext("change directory to the home directory by :cd"))
+  call <SID>BinOptionG("cdh", &cdh)
+endif
 call <SID>AddOption("cdpath", gettext("list of directory names used for :cd"))
 call <SID>OptionG("cd", &cd)
 if exists("+autochdir")