Merge "Bump the default from gnu++17 to gnu++20." into main am: 37d6943f

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2760825



Change-Id: Icea6c66af2d8b064b0a29071f61424ce01d42783
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>