Merge branch 'test_progs-stdio'
Stanislav Fomichev says:
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I was looking into converting test_sockops* to test_progs framework
and that requires using cgroup_helpers.c which rely on stdio/stderr.
Let's use open_memstream to override stdout into buffer during
subtests instead of custom test_{v,}printf wrappers. That lets
us continue to use stdio in the subtests and dump it on failure
if required.
That would also fix bpf_find_map which currently uses printf to
signal failure (missed during test_printf conversion).
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>