scx/selftests: Verify we can call create_dsq from prog_run

We already have some testcases verifying that we can call
BPF_PROG_TYPE_SYSCALL progs and invoke scx_bpf_exit(). Let's extend that to
also call scx_bpf_create_dsq() so we get coverage for that as well.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

tools/testing/selftests/sched_ext/prog_run.bpf.c

@@ -16,6 +16,7 @@ char _license[] SEC("license") = "GPL";
 SEC("syscall")
 int BPF_PROG(prog_run_syscall)
 {
+	scx_bpf_create_dsq(0, -1);
 	scx_bpf_exit(0xdeadbeef, "Exited from PROG_RUN");
 	return 0;
 }