Fix encryption/decryption of large blocks.

There's a long-standing bug (since ~Marshmallow) that causes
AndroidKeyStore to truncate large (>64 KiB) blocks of data.  This can
be avoided by callers by processing data in smaller chunks, and
smaller chunks are more memory-efficient while not being much (if any)
more time-efficient.  But, Keystore should handle large blocks
correctly.  This CL adds a test to all block cipher tests that
attempts to encrypt and then decrypt a 100 KiB block.

Bug: 123391046
Test:  CtsKeystoreTestCases
Change-Id: I0c0286fd5360d4fe62cbd8130aa0c17f97318801

keystore/java/android/security/keystore/KeyStoreCryptoOperationChunkedStreamer.java

@@ -162,15 +162,15 @@ class KeyStoreCryptoOperationChunkedStreamer implements KeyStoreCryptoOperationS
             }
 
             if ((opResult.output != null) && (opResult.output.length > 0)) {
-                if (inputLength > 0) {
+                if (inputLength + mBufferedLength > 0) {
                     // More output might be produced in this loop -- buffer the current output
                     if (bufferedOutput == null) {
                         bufferedOutput = new ByteArrayOutputStream();
-                        try {
-                            bufferedOutput.write(opResult.output);
-                        } catch (IOException e) {
-                            throw new ProviderException("Failed to buffer output", e);
-                        }
+                    }
+                    try {
+                        bufferedOutput.write(opResult.output);
+                    } catch (IOException e) {
+                        throw new ProviderException("Failed to buffer output", e);
                     }
                 } else {
                     // No more output will be produced in this loop