getaddrinfo: initialize addrinfo_sort_elem array to zero

resolv_rfc6724_sort() may not initialize the data member "src_addr"
of sort element while _find_src_addr() failed. Uninitialized "src_addr"
may cause unexpected rfc6724 sort result. Ex: _get_scope() uses
"src_addr" to compare sort element in _rfc6724_compare().

Test: atest ResolverTest
Bug: 247939181
Change-Id: I8d37cc127bdcac9b8092b45e1be6fe069999282a