ART: Use libcore's bp preupload check script

Add a preupload hook testing Blueprint files.

Test: m art
Test: manual
Change-Id: I04f7a93a4c9642d305dfa2407884c922cb68c084
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 60ad35c..7ebbce9 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -1,6 +1,10 @@
 [Hook Scripts]
 check_generated_tests_up_to_date = tools/test_presubmit.py
 
+# Ensure that bp files are correctly formatted.
+# Note: uses libcore's script.
+bpfmt-check = ${REPO_ROOT}/libcore/tools/check-bpfmt.sh ${PREUPLOAD_COMMIT}
+
 [Builtin Hooks]
 cpplint = true