selftests/bpf: Skip timer_interrupt case when bpf_timer is not supported

Like commit fbdd61c ("selftests/bpf: Skip timer cases when bpf_timer is not supported"),
'timer_interrupt' test case should be skipped if verifier rejects
bpf_timer with returning -EOPNOTSUPP.

cd tools/testing/selftests/bpf
./test_progs -t timer
461     timer_interrupt:SKIP
Summary: 6/0 PASSED, 7 SKIPPED, 0 FAILED

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250915121657.28084-1-leon.hwang@linux.dev

Author: Asphaltt

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

@@ -108,6 +108,10 @@ void test_timer_interrupt(void)
 	LIBBPF_OPTS(bpf_test_run_opts, opts);
 
 	skel = timer_interrupt__open_and_load();
+	if (!skel && errno == EOPNOTSUPP) {
+		test__skip();
+		return;
+	}
 	if (!ASSERT_OK_PTR(skel, "timer_interrupt__open_and_load"))
 		return;