SUNRPC: Let Kunit tests run with some enctypes compiled out

Allow the new GSS Kerberos encryption type test suites to run
outside of the kunit infrastructure. Replace the assertion that
fires when lookup_enctype() so that the case is skipped instead of
failing outright.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/auth_gss/gss_krb5_test.c

@@ -49,7 +49,8 @@ static void kdf_case(struct kunit *test)
 
 	/* Arrange */
 	gk5e = gss_krb5_lookup_enctype(param->enctype);
-	KUNIT_ASSERT_NOT_NULL(test, gk5e);
+	if (!gk5e)
+		kunit_skip(test, "Encryption type is not available");
 
 	derivedkey.data = kunit_kzalloc(test, param->expected_result->len,
 					GFP_KERNEL);
@@ -83,7 +84,8 @@ static void checksum_case(struct kunit *test)
 
 	/* Arrange */
 	gk5e = gss_krb5_lookup_enctype(param->enctype);
-	KUNIT_ASSERT_NOT_NULL(test, gk5e);
+	if (!gk5e)
+		kunit_skip(test, "Encryption type is not available");
 
 	Kc.len = gk5e->Kc_length;
 	Kc.data = kunit_kzalloc(test, Kc.len, GFP_KERNEL);
@@ -725,7 +727,8 @@ static void rfc3962_encrypt_case(struct kunit *test)
 
 	/* Arrange */
 	gk5e = gss_krb5_lookup_enctype(param->enctype);
-	KUNIT_ASSERT_NOT_NULL(test, gk5e);
+	if (!gk5e)
+		kunit_skip(test, "Encryption type is not available");
 
 	cbc_tfm = crypto_alloc_sync_skcipher(gk5e->aux_cipher, 0, 0);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cbc_tfm);
@@ -1319,7 +1322,8 @@ static void rfc6803_encrypt_case(struct kunit *test)
 
 	/* Arrange */
 	gk5e = gss_krb5_lookup_enctype(param->enctype);
-	KUNIT_ASSERT_NOT_NULL(test, gk5e);
+	if (!gk5e)
+		kunit_skip(test, "Encryption type is not available");
 
 	usage.data[3] = param->constant;
 
@@ -1810,7 +1814,8 @@ static void rfc8009_encrypt_case(struct kunit *test)
 
 	/* Arrange */
 	gk5e = gss_krb5_lookup_enctype(param->enctype);
-	KUNIT_ASSERT_NOT_NULL(test, gk5e);
+	if (!gk5e)
+		kunit_skip(test, "Encryption type is not available");
 
 	*(__be32 *)usage.data = cpu_to_be32(2);
 
@@ -1975,7 +1980,8 @@ static void encrypt_selftest_case(struct kunit *test)
 
 	/* Arrange */
 	gk5e = gss_krb5_lookup_enctype(param->enctype);
-	KUNIT_ASSERT_NOT_NULL(test, gk5e);
+	if (!gk5e)
+		kunit_skip(test, "Encryption type is not available");
 
 	cbc_tfm = crypto_alloc_sync_skcipher(gk5e->aux_cipher, 0, 0);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cbc_tfm);