Function btck_chain_contains 

pub unsafe extern "C" fn btck_chain_contains(
    chain: *const btck_Chain,
    block_tree_entry: *const btck_BlockTreeEntry,
) -> c_int

@brief Return true if the passed in chain contains the block tree entry.

@param[in] chain Non-null. @param[in] block_tree_entry Non-null. @return 1 if the block_tree_entry is in the chain, 0 otherwise.