patch 8.1.0534: MS-Windows installer uses different $HOME than Vim

Problem:    MS-Windows installer uses different $HOME than Vim.
Solution:   Use the Vim logic also in the MS-Windows installer. (Ken Takata,
            closes #3564)
diff --git a/src/misc1.c b/src/misc1.c
index 820f8f9..b1cc215 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -3905,6 +3905,8 @@
  *  - do mch_dirname() to get the real name of that directory.
  *  This also works with mounts and links.
  *  Don't do this for MS-DOS, it will change the "current dir" for a drive.
+ * For Windows:
+ *  This code is duplicated in init_homedir() in dosinst.c.  Keep in sync!
  */
 static char_u	*homedir = NULL;