Explicit init .rc user.

Set the user explicitly.

Bug: 276813155
Test: boot
Change-Id: I54c14c47a3435d72e00280cf663f23ffbb9659ee
diff --git a/vold.rc b/vold.rc
index 9474a1e..bf72b0c 100644
--- a/vold.rc
+++ b/vold.rc
@@ -6,4 +6,5 @@
     task_profiles ProcessCapacityHigh
     shutdown critical
     group root reserved_disk
+    user root
     reboot_on_failure reboot,vold-failed