package/cereal: fix CVE-2020-11105

package/cereal: fix CVE-2020-11105

Fix CVE-2020-11105: An issue was discovered in USC iLab cereal through
1.3.0. It employs caching of std::shared_ptr values, using the raw
pointer address as a unique identifier. This becomes problematic if an
std::shared_ptr variable goes out of scope and is freed, and a new
std::shared_ptr is allocated at the same address. Serialization fidelity
thereby becomes dependent upon memory layout. In short, serialized
std::shared_ptr variables cannot always be expected to serialize back
into their original values. This can have any number of consequences,
depending on the context within which this manifests.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>