runtime: checkptr incorrectly -race flagging when using &^ arithmetic [1.14 backport] #40968
Description
@dmitshur requested issue #40917 to be considered for backport to the next 1.14 minor release. (The original issue exists in 1.14 too, so per backport policy, it must be considered for backporting to both 1.15 and 1.14.)
See the corresponding 1.15 backport issue #40934 for more details.
/cc @mdempsky