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

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

Change-Id: I2140140a0b65b04a8e12e3837b33659aec05190d