Use unique_ptr in dns_getaddrinfo()

This simplifies memory management a bit. In fact, we don't even bother
checking for memory allocation failures because 'new' aborts instead of
returning null to the caller.

Test: atest resolv_integration_test
Change-Id: I6456922f4ca6d04d67fedc8873b0c32becf1d3dc
1 file changed