bpf, seccomp: fix false positive preemption splat for cbpf->ebpf progs

In 568f196756ad ("bpf: check that BPF programs run with preemption disabled")
a check was added for BPF_PROG_RUN() that for every invocation preemption is
disabled to not break eBPF assumptions (e.g. per-cpu map). Of course this does
not count for seccomp because only cBPF -> eBPF is loaded here and it does
not make use of any functionality that would require this assertion. Fix this
false positive by adding and using SECCOMP_RUN() variant that does not have
the cant_sleep(); check.

Fixes: 568f196756ad ("bpf: check that BPF programs run with preemption disabled")
Reported-by: syzbot+8bf19ee2aa580de7a2a7@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>