Fixing assignment issue from clone()

The unique_ptr being returned from clone() was getting directly assigned
to a cppbor::array(), causing a var arg constructor to be called on
assignment which was handling the returned pointer by wrapping its
contents in another array. This change properly moves the dereferenced
value out the call to clone() instead.

Ignore-AOSP-First: CP from aosp to sc-dev
Bug: 189018262
Test: Prod keys are signed by the server.
Change-Id: I6ee5d8bb2a70aeaff53ab23d9ebdbd45a84f2543
1 file changed