Merge "Bump default experimental from gnu++2a to gnu++2b." into main am: a1d45b8e

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2832038



Change-Id: I8e2a821c7284411a0e5348ebb9aff3ebebd68e84
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>