Use the global default cpp_std. am: 65175a332b

Original change: https://android-review.googlesource.com/c/platform/external/private-join-and-compute/+/3113842

Change-Id: I4636e8262e94e1b7c21590972b2ef466329c9501
Signed-off-by: Automerger Merge Worker <[email protected]>