ANDROID: rust: Enable KCFI support when available

On newer clang, a flag is available which makes KCFI compatibility with
rustc possible without significant contortions.

This is Android specific because Rust KCFI is incomplete, and we are
using the binder driver as a staging ground to fix it. This patch is
intended to go upstream once the compiler behaves properly.

Signed-off-by: Matthew Maurer <mmaurer@google.com>
Bug: 316623888
Change-Id: I2118224e0e85424298c5315392917f2699f75af7