Do not pass NULL to xccdf_benchmark_get_schema_version
Do not pass NULL to xccdf_benchmark_get_schema_version

Addressing (CWE-476):
src/XCCDF/item.c:834: var_deref_model: Passing null pointer "top_benchmark"
to "xccdf_benchmark_get_schema_version", which dereferences it.

Hexadorsimal/openscap,postfix/openscap,redhatrises/openscap,jan-cerny/openscap,OpenSCAP/openscap,Hexadorsimal/openscap,redhatrises/openscap,openprivacy/openscap,mpreisler/openscap,redhatrises/openscap,ybznek/openscap,jan-cerny/openscap,mpreisler/openscap,OpenSCAP/openscap,ybznek/openscap,Hexadorsimal/openscap,openprivacy/openscap,ybznek/openscap,jan-cerny/openscap,mpreisler/openscap,OpenSCAP/openscap,ybznek/openscap,openprivacy/openscap,openprivacy/openscap,mpreisler/openscap,Hexadorsimal/openscap,Hexadorsimal/openscap,postfix/openscap,openprivacy/openscap,postfix/openscap,OpenSCAP/openscap,mpreisler/openscap,postfix/openscap,jan-cerny/openscap,mpreisler/openscap,postfix/openscap,OpenSCAP/openscap,openprivacy/openscap,postfix/openscap,ybznek/openscap,ybznek/openscap,jan-cerny/openscap,OpenSCAP/openscap,jan-cerny/openscap,redhatrises/openscap,redhatrises/openscap,Hexadorsimal/openscap,redhatrises/openscap