Global apreq_atoi64f (const char *s): What happens when s is malformed? Should this return an unsigned value instead?
Global apreq_atoi64t (const char *s): What happens when s is malformed? Should this return an unsigned value instead?
Global apreq_brigade_concat (apr_pool_t *pool, const char *temp_dir, apr_size_t brigade_limit, apr_bucket_brigade *out, apr_bucket_brigade *in): Flesh out these error codes, making them as explicit as possible.