Adjust nonce for v15 servers

Merge from Widevine repo of http://go/wvgerrit/102783

When OEMCrypto is v16, but the license server is v15, we should not
create a new nonce for a license renewal. However, the request does
need a nonce or the license server will not generate a valid key
control block. So we should use the nonce that came from the original
license.

Bug: 160676790
Test: tested playback using netflix
Test: GTS tests. http://go/forrest-run/L55100000642199761
Change-Id: Ie1644b5abe0662387edf01f6110d82f70a64df6c

libwvdrmengine/cdm/core/include/license.h

@@ -176,6 +176,9 @@ class CdmLicense {
   // HandleKeyResponse
   VersionInfo latest_service_version_;
 
+  // The nonce used in the original license request.
+  uint32_t license_nonce_;
+
 #if defined(UNIT_TEST)
   friend class CdmLicenseTestPeer;
 #endif