rust-bootstrap: update to 1.47.0

BUG=None
TEST=emerge rust-bootstrap

Change-Id: I762d97f9ec2dd42f19d07de7d2c314f2512f62b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2555621
Reviewed-by: Tiancong Wang <tcwang@google.com>
Commit-Queue: Tiancong Wang <tcwang@google.com>
Tested-by: Tiancong Wang <tcwang@google.com>
9 files changed