patch 8.1.1746: ":dl" is seen as ":dlist" instead of ":delete"

Problem:    ":dl" is seen as ":dlist" instead of ":delete".
Solution:   Do not use cmdidxs2[] if the length is 1. (closes #4721)
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index eb014a9..a0898dc 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -106,6 +106,7 @@
 	test_ex_equal \
 	test_ex_undo \
 	test_ex_z \
+	test_excmd \
 	test_exec_while_if \
 	test_execute_func \
 	test_exists \
@@ -328,6 +329,7 @@
 	test_erasebackword.res \
 	test_escaped_glob.res \
 	test_eval_stuff.res \
+	test_excmd.res \
 	test_exec_while_if.res \
 	test_exists.res \
 	test_exists_autocmd.res \