Upgrade rust/crates/protobuf to 2.17.0

* Android.bp was regenerated. New rustc warnings were found.
* Keep local change in src/lib.rs to include out/version.rs.
* Update out/version.rs to the new version.

Change-Id: I9c2f7d412dcd42fe3769505629e05ab949300fe6
Test: make
diff --git a/src/ext.rs b/src/ext.rs
index 70b7439..a1c18f6 100644
--- a/src/ext.rs
+++ b/src/ext.rs
@@ -6,8 +6,8 @@
 
 use std::marker::PhantomData;
 
-use core::Message;
-use types::ProtobufType;
+use crate::message::Message;
+use crate::types::ProtobufType;
 
 /// Optional ext field
 pub struct ExtFieldOptional<M: Message, T: ProtobufType> {