Address test failures on Java 11. (#1189)

xecPrivateKeySpec failure was a copy pasta bug but only
shows up on 11 due to missing XEC classes on earlier Java.

The other failure in keyspec_Fail(), looks like it
was due to the KeyFactory implementation iterating over
SPIs on failure, and in OpenJDK 11 there is an XDH
KeyFactory, although I'm unsure why it was rejecting
what should be valid PKCS#8 data...

common/src/test/java/org/conscrypt/javax/crypto/XdhKeyFactoryTest.java

@@ -52,7 +52,8 @@ public class XdhKeyFactoryTest {
             decodeBase64("MCowBQYDK2VuAyEAeNH3ZKS7SCZT495bvIvoyYB9PNIFefUSTfi6eNhFYXA=");
     private final byte[] privateKeyPkcs8Bytes =
             decodeBase64("MC4CAQAwBQYDK2VuBCIEIADBSHEZer+X0ZdqReHuMDx61nQwWwNHOnx9HHRNJBJK");
-    private final KeyFactory factory = KeyFactory.getInstance("XDH");
+    private final KeyFactory factory =
+            KeyFactory.getInstance("XDH", TestUtils.getConscryptProvider());
     private final PublicKey publicKey =
             factory.generatePublic(new X509EncodedKeySpec(publicKeyX509Bytes));
     private final PrivateKey privateKey =
@@ -143,8 +144,6 @@ public void privateKeySpec_Success() throws Exception {
     public void keySpec_Fail() throws Exception {
         assertThrows(InvalidKeySpecException.class,
                 () -> factory.getKeySpec(publicKey, PKCS8EncodedKeySpec.class));
-        PrivateKey privateKey = factory.generatePrivate(
-                new PKCS8EncodedKeySpec(privateKeyPkcs8Bytes));
         assertThrows(InvalidKeySpecException.class,
                 () -> factory.getKeySpec(privateKey, X509EncodedKeySpec.class));
 
@@ -187,7 +186,7 @@ public void xecPrivateKeySpec() throws Exception {
         @SuppressWarnings("unchecked")
         Class<? extends KeySpec> javaClass = (Class<? extends KeySpec>)
                 TestUtils.findClass("java.security.spec.XECPrivateKeySpec");
-        PrivateKey key = factory.generatePrivate(new X509EncodedKeySpec(privateKeyPkcs8Bytes));
+        PrivateKey key = factory.generatePrivate(new PKCS8EncodedKeySpec(privateKeyPkcs8Bytes));
         KeySpec spec = factory.getKeySpec(key, javaClass);
         assertNotNull(spec);
     }