Merge branch 'bpf-prog-stats'

Alexei Starovoitov says:

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Introduce per program stats to monitor the usage BPF.

v2->v3:
- rename to run_time_ns/run_cnt everywhere

v1->v2:
- fixed u64 stats on 32-bit archs. Thanks Eric
- use more verbose run_time_ns in json output as suggested by Andrii
- refactored prog_alloc and clarified behavior of stats in subprogs
====================

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>