patch 9.0.1601: filetype detection fails for *.conf file without comments

Problem:    Filetype detection fails for *.conf file without comments.
            (Dmitrii Tcyganok)
Solution:   Use "conf" filetype as a fallback for an empty .conf file.
            (closes #12487, closes #12483)
diff --git a/src/version.c b/src/version.c
index b854893..e373686 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1601,
+/**/
     1600,
 /**/
     1599,