Add post_update.sh and regenerate .bp am: 0bd5ab11c9 am: 44ea9e98d8 am: 91eff06017 am: b786f3fc7d am: cad1e905bd

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/clang-sys/+/1434797

Change-Id: Id75068a624ea536e84f40af0a928be0fada1f165