Remove the lock in ParcelableHolder

As we removed the lock for ParcelableHolder in Java(aosp/1458065), the
lock both in NDK and c++ side will be removed as well. Instead the lock is provided
as default, the users should use their own lock if necessary.

Bug: 146611855
Test: CtsNdkBinderTest
Change-Id: I334796ecd49d30b53e05da5fcef7d2cfe65164b9