patch 8.1.1805: au_did_filetype is declared twice

Problem:    Au_did_filetype is declared twice.
Solution:   Remove it from autocmd.c. (closes #4767)
diff --git a/src/version.c b/src/version.c
index d249d85..e2ebd89 100644
--- a/src/version.c
+++ b/src/version.c
@@ -774,6 +774,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1805,
+/**/
     1804,
 /**/
     1803,