container/seccomp: alias libseccomp types

This enables tests to refer to these types and check its size.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/seccomp/syscall_test.go

@@ -1,7 +1,9 @@
 package seccomp
 
 import (
+	"reflect"
 	"testing"
+	"unsafe"
 
 	"hakurei.app/container/std"
 )
@@ -20,3 +22,18 @@ func TestSyscallResolveName(t *testing.T) {
 		})
 	}
 }
+
+func TestRuleSize(t *testing.T) {
+	assertSize[NativeRule, syscallRule](t)
+	assertSize[ScmpDatum, scmpDatum](t)
+	assertSize[ScmpArgCmp, scmpArgCmp](t)
+}
+
+// assertSize asserts that native and equivalent are of the same size.
+func assertSize[native, equivalent any](t *testing.T) {
+	got := unsafe.Sizeof(*new(native))
+	want := unsafe.Sizeof(*new(equivalent))
+	if got != want {
+		t.Fatalf("%s: %d, want %d", reflect.TypeFor[native]().Name(), got, want)
+	}
+}