Fix getSecureStop returns zero opaque data intermittently.

Merge from http://go/wvgerrit/69587

In getSecureStop, the life of cdmStop will expire when
leaving the if (isCmdResponseTypeSuccess()) scope.
Since setToExternal() which is called by toHidlVec()
only performs a pointer assignment, the content of cdmStop
is lost and secureStop.opaqueData will have all zeros.

Test: netflix streaming and offline playback

Test: Play Movies & TV

Test: GTS test
  -m GtsMediaTestCases --test com.google.android.media.gts.MediaDrmTest#testWidevineApi28

Test: GTS test
  -m GtsMediaTestCases

bug: 120624463
Change-Id: I787e2b931561f07ca7346cb5a8968b868c08cee8

libwvdrmengine/mediadrm/src_hidl/WVDrmPlugin.cpp

@@ -671,7 +671,9 @@ Return<void> WVDrmPlugin::getSecureStop(
     _hidl_cb(Status::BAD_VALUE, SecureStop());
     return Void();
   }
+
   const std::vector<uint8_t> id = toVector(secureStopId);
+  std::vector<uint8_t> cdmStopVec;
   SecureStop secureStop;
 
   CdmIdentifier identifier;
@@ -687,7 +689,6 @@ Return<void> WVDrmPlugin::getSecureStop(
       mPropertySet.app_id(), cdmSsId, identifier, &cdmUsageInfo);
 
   if (isCdmResponseTypeSuccess(res)) {
-    std::vector<uint8_t> cdmStopVec;
     for (CdmUsageInfo::const_iterator iter = cdmUsageInfo.begin();
          iter != cdmUsageInfo.end();
          ++iter) {