Fix: Add TEST_PROJECT injected var to make-unit

This was missed in the last commit, when make-unit.sh was modified
so that it could be set to something that isn't the triggering
gerrit project.

This commit also improves the feedback from make-unit.sh if the
Makefile isn't found.

Signed-off-by: Eric Ball <eball@linuxfoundation.org>
Change-Id: I12b78b94edffb1a80e462450cc2e5b8883e10de2
diff --git a/jjb/make-unit.yaml b/jjb/make-unit.yaml
index 51a1569..f81d714 100644
--- a/jjb/make-unit.yaml
+++ b/jjb/make-unit.yaml
@@ -48,6 +48,7 @@
             UNIT_TEST_TARGETS={unit-test-targets}
             UNIT_TEST_KEEP_GOING={unit-test-keep-going}
             GOPROXY=https://proxy.golang.org
+            TEST_PROJECT={project}
       - shell: !include-raw-escape: shell/make-unit.sh
 
     publishers: