Upgrade itertools to 0.10.5

This project was upgraded with external_updater.
Usage: tools/external_updater/updater.sh update rust/crates/itertools
For more info, check https://cs.android.com/android/platform/superproject/+/master:tools/external_updater/README.md

Test: TreeHugger
Change-Id: I04ecd1d5827d6d1822997f324e6bac8e8bd8ea83
diff --git a/src/impl_macros.rs b/src/impl_macros.rs
index 5772bae..a029843 100644
--- a/src/impl_macros.rs
+++ b/src/impl_macros.rs
@@ -15,6 +15,7 @@
 
 macro_rules! clone_fields {
     ($($field:ident),*) => {
+        #[inline] // TODO is this sensible?
         fn clone(&self) -> Self {
             Self {
                 $($field: self.$field.clone(),)*