libct/cg/fscommon.OpenFile: reverse checks order
libct/cg/fscommon.OpenFile: reverse checks order

In case openat2() is not available, it does not make sense to calculate
relpath (and check if path has /sys/fs/cgroup prefix).

Reverse the order of checks to not do that in case openat2 is not
available.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

rhatdan/runc,rhatdan/runc,opencontainers/runc,dqminh/runc,kolyshkin/runc,dqminh/runc,rhatdan/runc,opencontainers/runc,kolyshkin/runc,opencontainers/runc,opencontainers/runc,rhatdan/runc,dqminh/runc,kolyshkin/runc,kolyshkin/runc,dqminh/runc