Add bootctl for vold

Allows checkpoint commands to check A/B update status

Test: vdc checkpoint startCheckpoint -1
Bug: 111020314
Change-Id: I086db548d55176bf88211001c7c1eecb8c50689e

public/vold.te

@@ -164,6 +164,9 @@ hal_client_domain(vold, hal_keymaster)
 # talk to health storage HAL
 hal_client_domain(vold, hal_health_storage)
 
+# talk to bootloader HAL
+hal_client_domain(vold, hal_bootctl)
+
 # Access userdata block device.
 allow vold userdata_block_device:blk_file rw_file_perms;
 
@@ -266,6 +269,7 @@ neverallow vold {
   -hal_health_storage_server
   -hal_keymaster_server
   -hal_system_suspend_server
+  -hal_bootctl
   -healthd
   -hwservicemanager
   -servicemanager