Log Message:
abseil: updated to 20211102.0

Abseil LTS 20211102

What's New:

absl::Cord is now implemented as a b-tree. The new implementation offers \ 
improved performance in most workloads.
absl::SimpleHexAtoi() has been added to strings library for parsing hexadecimal \ 
strings.

Breaking Changes:

Bazel builds now depend on the bazelbuild/platforms repository. See Abseil's \ 
WORKSPACE file for an example of how to add this dependency.