Upgrade toybox to 7768ecdf2a0d847097856988557de76a2af850f8 am: 256febc76b

Original change: https://android-review.googlesource.com/c/platform/external/toybox/+/2183540

Change-Id: I54a9f002a29527475f6af29f09b93bd5c6a79647
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>