point to new repo hooks for mainline uploads

Bug: 157501573
Test: upload
Change-Id: I976d533136028cfc29569674715b90cf93c7606f

PREUPLOAD.cfg

diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
new file mode 100644
index 0000000..ecf8b8e
--- /dev/null
+++ b/PREUPLOAD.cfg
@@ -0,0 +1,2 @@
+[Hook Scripts]
+mainline_hook = ${REPO_ROOT}/frameworks/av/tools/mainline_hook_project.sh