Make crate vendor_available, use public header am: 2e4b28ef02 am: c213cb93db am: bc7be13165

Original change: https://android-review.googlesource.com/c/platform/system/librustutils/+/2104868

Change-Id: I0c6cc33ab82d35a71c8485d3283dc4c4e7d80cdf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>