Expose binder security context to rust binder services

This patch exposes AIBinder_setRequestingSid and AIBinder_getCallingSid
to binder services written in Rust. This is required by services to
effectively enforce SEPolicy because relying only on the caller's PID is
racy.

Bug: 165070170
Test: atest rustBinderTest
Change-Id: Iae25d4fedded7d133354ba4c82527f33e5d5e1ce
diff --git a/libs/binder/rust/src/binder.rs b/libs/binder/rust/src/binder.rs
index d55eafe..d8e0609 100644
--- a/libs/binder/rust/src/binder.rs
+++ b/libs/binder/rust/src/binder.rs
@@ -98,6 +98,9 @@
     /// Send a ping transaction to this object
     fn ping_binder(&mut self) -> Result<()>;
 
+    /// Indicate that the service intends to receive caller security contexts.
+    fn set_requesting_sid(&mut self, enable: bool);
+
     /// Dump this object to the given file handle
     fn dump<F: AsRawFd>(&mut self, fp: &F, args: &[&str]) -> Result<()>;