patch 7.4.1989
Problem:    filter() and map() only accept a string argument.
Solution:   Implement using a Funcref argument (Yasuhiro Matsumoto, Ken
            Takata)
diff --git a/src/Makefile b/src/Makefile
index 3aeac7d..4deb4a2 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2031,6 +2031,7 @@
 	test_farsi \
 	test_feedkeys \
 	test_file_perm \
+	test_filter_map \
 	test_fnamemodify \
 	test_glob2regpat \
 	test_goto \