No need for the extra include. test_progs.h already includes bpf_util.h, please check such trivialities before submission. Simple grep would have revealed use of ARRAY_SIZE() in various places under tools/testing/selftests/bpf/prog_tests/.
Actually, ARRAY_SIZE() in ./include/linux/kernel.h is diffrent from the one defined in bpf_util.h:
./include/linux/kernel.h #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
./tools/testing/selftests/bpf/bpf_util.h #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
__must_be_array() ensures arr is an array, which is better than the one defined in bpf_util.h
here are many more similar occurrences. Please just send one cleanup patch to reduce churn in the git log.
Yes, I will commit another patch.