Restore Abseil submodule to main.
diff --git a/third_party/abseil-cpp b/third_party/abseil-cpp index c2435f8..29bf808 160000 --- a/third_party/abseil-cpp +++ b/third_party/abseil-cpp
@@ -1 +1 @@ -Subproject commit c2435f8342c2d0ed8101cb43adfd605fdc52dca2 +Subproject commit 29bf8085f3bf17b84d30e34b3d7ff8248fda404e