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/singular.rs b/src/singular.rs
index 71d4f0a..ef04d2f 100644
--- a/src/singular.rs
+++ b/src/singular.rs
@@ -8,7 +8,7 @@
 use std::mem;
 use std::option;
 
-use clear::Clear;
+use crate::clear::Clear;
 
 /// Like `Option<T>`, but keeps the actual element on `clear`.
 pub struct SingularField<T> {
@@ -552,7 +552,7 @@
 #[cfg(test)]
 mod test {
     use super::SingularField;
-    use clear::Clear;
+    use crate::clear::Clear;
 
     #[test]
     fn test_set_default_clears() {