CVE-2026-74338 bpf: Reject sleepable BPF_LSM_CGROUP programs at load time

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject sleepable BPFLSMCGROUP programs at load time The cgroup shim runs under rcureadlockdontmigrate, so we should not attach any sleepable BPF programs there. Add support to the verifier to explicitly reject attempts to lo...