Bug#1008730: abseil: Please update to latest upstream version

[Benjamin Barenblat]

The latest Abseil release requires a prerelease version of googletest,
so I’m deliberately waiting to package it. I’ve mentioned the problem to
people who work on googletest at Google, and a new googletest upstream
release is in the pipeline. In the meantime, I’d be happy to backport
some patches – are there any that you’ve identified as good candidates?