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/shell/make-unit.sh b/jjb/shell/make-unit.sh
index 03f98ef..ac0bd6e 100755
--- a/jjb/shell/make-unit.sh
+++ b/jjb/shell/make-unit.sh
@@ -47,7 +47,7 @@
 UNIT_TEST_KEEP_GOING=${UNIT_TEST_KEEP_GOING:-false}
 
 if [ ! -f "$test_path/Makefile" ]; then
-  echo "Makefile not found at $test_path!"
+  echo "Makefile not found at ${test_path}/Makefile"
   exit 1
 else
   pushd "$test_path"