force make error to exit 1

This is a deliberate error to test code test.yml.

TODO: Remove this line after we see what happens:

```diff
diff --git a/Makefile b/Makefile
index 85d01c05..d3ea5197 100644
--- a/Makefile
+++ b/Makefile
@@ -915,6 +915,7 @@ test:
        ${E} ${MAKE} ${MAKE_CD_Q} -C test_ioccc $@
        ${E} ${RM} -f jparse/test_jparse/pr_jparse_test
        ${S} echo
+       exit 1 # XXX - deliberate failure to test code test.yml - XXX
        ${S} echo "${OUR_NAME}: make $@ ending"

 # run test-chkentry on test_JSON files
```

Makefile

@@ -915,6 +915,7 @@ test:
 	${E} ${MAKE} ${MAKE_CD_Q} -C test_ioccc $@
 	${E} ${RM} -f jparse/test_jparse/pr_jparse_test
 	${S} echo
+	exit 1 # XXX - deliberate failure to test code test.yml - XXX
 	${S} echo "${OUR_NAME}: make $@ ending"
 
 # run test-chkentry on test_JSON files