Upgrade toybox to 7c6aecd477a9b898df981197088c9e1d5775fe9c

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

Test: TreeHugger
Change-Id: If64ef2632aa46dcb613767151719434e6ac28b2f