patch 8.0.1336: cannot use imactivatefunc() unless compiled with +xim

Problem:    Cannot use imactivatefunc() unless compiled with +xim.
Solution:   Allow using imactivatefunc() when not compiled with +xim.
            (Yasuhiro Matsumoto, closes #2349)
diff --git a/src/Makefile b/src/Makefile
index 09cf21e..7ccd766 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2190,6 +2190,7 @@
 	test_highlight \
 	test_history \
 	test_hlsearch \
+	test_iminsert \
 	test_increment \
 	test_increment_dbcs \
 	test_ins_complete \