patch 8.0.0613: the conf filetype is used before ftdetect from packages

Problem:    The conf filetype detection is done before ftdetect scripts from
            packages that are added later.
Solution:   Add the FALLBACK argument to :setfiletype. (closes #1679,
            closes #1693)
diff --git a/src/Makefile b/src/Makefile
index ddb61dc..8fa004e 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2133,6 +2133,7 @@
 	test_feedkeys \
 	test_file_perm \
 	test_fileformat \
+	test_filetype \
 	test_filter_cmd \
 	test_filter_map \
 	test_findfile \