features: prog_test - make LircMode2 test optional again

As it turns out, some mainstream distributions (Ubuntu, for one) build with
LIRC disabled, which also disables this prog type. To keep the test suite
compatible with most hosts, make it optional once more.

features/prog_test.go

@@ -66,6 +66,13 @@ func TestHaveProgType(t *testing.T) {
 			testutils.SkipOnOldKernel(t, minVersion, feature)
 
 			if err := HaveProgType(pt); err != nil {
+				if pt == ebpf.LircMode2 {
+					// CI kernels are built with CONFIG_BPF_LIRC_MODE2, but some
+					// mainstream distro's don't ship with it. Make this prog type
+					// optional to retain compatibility with those kernels.
+					testutils.SkipIfNotSupported(t, err)
+				}
+
 				t.Fatalf("Program type %s isn't supported even though kernel is at least %s: %v", pt.String(), minVersion, err)
 			}
 		})