tests: Fill fuzzing coverage gaps for functions in primitives/block.h
tests: Fill fuzzing coverage gaps for functions in primitives/block.h

Former-commit-id: 8d6f3c4777ad3a3d53bb3cebdc83200efcc2c8ec
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin