Add pkey_alloc(2), pkey_free(2) and pkey_mprotect(2) in seccomp default profile. pkey_alloc(2), pkey_free(2) and pkey_mprotect(2) can only configure the calling process's own memory, so they are existing "safe for everyone" syscalls. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>