patch 8.0.0493: crash with cd command with very long argument

Problem:    Crash with cd command with very long argument.
Solution:   Check for running out of space. (Dominique pending, closes #1576)
diff --git a/src/Makefile b/src/Makefile
index 551bb6f..3d13b85 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2096,6 +2096,7 @@
 	test_backspace_opt \
 	test_breakindent \
 	test_bufwintabinfo \
+	test_cd \
 	test_cdo \
 	test_changedtick \
 	test_channel \