Make libbinder_rs vendor available.

Add vendor_available: true to libbinder_rs and dependencies.
Also remove set_requesting_sid conditionally if building the vendor
variant.

Test: Vendor components can compile and link against libbinder_rs.
Bug: 198197213
Change-Id: I9ad9ed226e76c16bff7d3feb201fd9fef20ad934
diff --git a/libs/binder/rust/src/proxy.rs b/libs/binder/rust/src/proxy.rs
index a8d0c33..d734866 100644
--- a/libs/binder/rust/src/proxy.rs
+++ b/libs/binder/rust/src/proxy.rs
@@ -324,6 +324,7 @@
         status_result(status)
     }
 
+    #[cfg(not(android_vndk))]
     fn set_requesting_sid(&mut self, enable: bool) {
         unsafe { sys::AIBinder_setRequestingSid(self.as_native_mut(), enable) };
     }