patch 8.0.1242: function argument with only dash is seen as number zero

Problem:    Function argument with only dash is seen as number zero. (Wang
            Shidong)
Solution:   See a dash as a string. (Christian Brabandt)
diff --git a/src/Makefile b/src/Makefile
index 0b95c6e..9258956 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2189,6 +2189,7 @@
 	test_hlsearch \
 	test_increment \
 	test_increment_dbcs \
+	test_ins_complete \
 	test_job_fails \
 	test_join \
 	test_json \