It's been more than 3 years since -pgo-instr-old-cfg-hashing was
introduced by:
commit 120e66b3418b37b95fc1dbbb23e296a602a24fa8
Author: Hiroshi Yamauchi <yamauchi@google.com>
Date: Tue Jul 28 10:09:49 2020 -0700
I don't think anyone really cares about the ability to use the old CFG
hashing at this point.