Check size of grantors before indexing into the vec am: 2b686fcd97 am: ca82973033 am: 75b22bfaa5 am: 683af4f033 am: 7a75a85d7d

Original change: https://android-review.googlesource.com/c/platform/system/libhidl/+/2113745

Change-Id: Ifcb885ebca8eb759a9093303b60a5cdb58ab36aa
Signed-off-by: Automerger Merge Worker <[email protected]>