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: 4787d71d829a1c9658187f72a2d2e498097302ab
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin