bpf/test_run: support cgroup local storage

bpf/test_run: support cgroup local storage

Allocate a temporary cgroup storage to use for bpf program test runs.

Because the test program is not actually attached to a cgroup,
the storage is allocated manually just for the execution
of the bpf program.

If the program is executed multiple times, the storage is not zeroed
on each run, emulating multiple runs of the program, attached to
a real cgroup.

Signed-off-by: Roman Gushchin <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Acked-by: Martin KaFai Lau <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>