Merge "Upgrade rust/crates/rustc-demangle to 0.1.21" am: 8758877a8d am: d72e97de62

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/rustc-demangle/+/1833617

Change-Id: I5a16b7b14efbd01f03cd40629cfda8d56ae744ac