selftests/bpf: Skip test when perf_event_open returns EOPNOTSUPP

When testing send_signal and stacktrace_build_id_nmi using the riscv sbi
pmu driver without the sscofpmf extension or the riscv legacy pmu driver,
then failures as follows are encountered:

test_send_signal_common:FAIL:perf_event_open unexpected perf_event_open: actual -1 < expected 0
#272/3 send_signal/send_signal_nmi:FAIL

test_stacktrace_build_id_nmi:FAIL:perf_event_open err -1 errno 95
#304 stacktrace_build_id_nmi:FAIL

The reason is that the above pmu driver or hardware does not support
sampling events, that is, PERF_PMU_CAP_NO_INTERRUPT is set to pmu
capabilities, and then perf_event_open returns EOPNOTSUPP. Since
PERF_PMU_CAP_NO_INTERRUPT is not only set in the riscv-related pmu driver,
it is better to skip testing when this capability is set.

Signed-off-by: Pu Lehui <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Acked-by: Daniel Borkmann <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/prog_tests/send_signal.c

···
 	pmu_fd = syscall(__NR_perf_event_open, &attr, 0 /* pid */,
 			 -1 /* cpu */, -1 /* group_fd */, 0 /* flags */);
 	if (pmu_fd == -1) {
-		if (errno == ENOENT) {
+		if (errno == ENOENT || errno == EOPNOTSUPP) {
 			printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
 			       __func__);
 			test__skip();

tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c

···
 	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
 			 0 /* cpu 0 */, -1 /* group id */,
 			 0 /* flags */);
-	if (pmu_fd < 0 && errno == ENOENT) {
+	if (pmu_fd < 0 && (errno == ENOENT || errno == EOPNOTSUPP)) {
 		printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__);
 		test__skip();
 		goto cleanup;