internal/pkg: transparently degrade landlock in tests

This does not test package container, so should transparently cope with Landlock LSM being unavailable.

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

internal/pkg/pkg_test.go

@@ -289,8 +289,17 @@ func checkWithCache(t *testing.T, testCases []cacheTestCase) {
 			msg := message.New(log.New(os.Stderr, "cache: ", 0))
 			msg.SwapVerbose(testing.Verbose())
 
+			flags := tc.flags
+			if _, err := container.LandlockGetABI(); err != nil {
+				if !errors.Is(err, syscall.ENOSYS) {
+					t.Fatalf("LandlockGetABI: error = %v", err)
+				}
+				flags |= pkg.CHostAbstract
+				t.Log("Landlock LSM is unavailable, setting CHostAbstract")
+			}
+
 			var scrubFunc func() error // scrub after hashing
-			if c, err := pkg.Open(t.Context(), msg, tc.flags, 1<<4, base); err != nil {
+			if c, err := pkg.Open(t.Context(), msg, flags, 1<<4, base); err != nil {
 				t.Fatalf("Open: error = %v", err)
 			} else {
 				t.Cleanup(c.Close)