to return a linked lists of results. These were also modified to internally
use the ares_data memory struct and as such its result must be free'ed with
ares_free_data().

MUST be valid and they are dereferenced further down in the function
unconditionally!

changed u_int16_t to unsigned short because it is the only place within ares and curl where such a type would be used;
also it broke many autobuilds. We should probably introduce an ares_port_t if we want to use a type here.