Do not verify decrypt hash when no key selected

Merge from Widevine repo of http://go/wvgerrit/101143

This CL removes the check for a decrypt hash error when CopyBuffer is
used instead of DecryptCenc because a key was not selected.

We also remove the attempt to check the decrypt hash when there are
multiple buffers, because that is not well defined behavior.

Bug: 155185867
Bug: 155192141
Test: ran unit tests on taimen and on v16  reference oemcrypto
Change-Id: I640e904e256f0913ca606bb5db891430b23f44a3

libwvdrmengine/oemcrypto/test/oemcrypto_test.cpp

@@ -2203,10 +2203,11 @@ class OEMCryptoSessionTestsDecryptTests
   void TestDecryptCENC() {
     OEMCryptoResult sts;
 
+    // OEMCrypto only supports providing a decrypt hash for one sample.
+    if (samples_.size() > 1) verify_crc_ = false;
+
     // If supported, check the decrypt hashes.
     if (verify_crc_) {
-      // OEMCrypto only supports providing a decrypt hash for the first sample
-      // in the sample array.
       const TestSample& sample = samples_[0];
 
       uint32_t hash =
@@ -2261,7 +2262,7 @@ class OEMCryptoSessionTestsDecryptTests
         }
       }
     }
-    if (global_features.supports_crc) {
+    if (verify_crc_) {
       uint32_t frame;
       ASSERT_EQ(OEMCrypto_GetHashErrorCode(session_.session_id(), &frame),
                 OEMCrypto_SUCCESS);