Upgrade rust/crates/protobuf-codegen to 2.17.0

* Android.bp was regenerated. New rurstc warnings were found.
* Keep local change in src/lib.rs; set rust-protobuf version to "2.17.0".

Change-Id: I84fd880955dad26e4490b5110bd44573fde0da02
Test: make
diff --git a/src/inside.rs b/src/inside.rs
index 2590e9e..bbdcfdb 100644
--- a/src/inside.rs
+++ b/src/inside.rs
@@ -4,8 +4,7 @@
 /// used inside or outside of protobuf crate.
 pub(crate) fn protobuf_crate_path(customize: &Customize) -> &str {
     match customize.inside_protobuf {
-        // Can't use `crate::` paths before Rust 1.32.0
-        //Some(true) => "crate",
+        Some(true) => "crate",
         _ => "::protobuf",
     }
 }