creates an empty lwres_conf_t structure for lightweight resolver context ctx.
lwres_conf_clear() frees up all the internal memory used by that lwres_conf_t structure in resolver context ctx.
lwres_conf_parse() opens the file filename and parses it to initialise the resolver context ctx's lwres_conf_t structure.
lwres_conf_print() prints the lwres_conf_t structure for resolver context ctx to the FILE fp.
lwres_conf_parse() returns LWRES_R_SUCCESS if it successfully read and parsed filename. It returns LWRES_R_FAILURE if filename could not be opened or contained incorrect resolver statements.
lwres_conf_print() returns LWRES_R_SUCCESS unless an error occurred when converting the network addresses to a numeric host address string. If this happens, the function returns LWRES_R_FAILURE.