mapping addition.
(ga_clone): Just call ga_dup from here.
(ga_duplist): New function to duplicate list of struct addrinfo.
(ga_echeck): Don't check a_flags, it already happened in
cygwin_getaddrinfo.
(cygwin_freeaddrinfo): Always call ipv4_freeaddrinfo.
(cygwin_getaddrinfo): Use new wincap.supports_all_posix_ai_flags
flag rather than wincap.has_gaa_on_link_prefix. Always duplicate
WinSock's addrinfo list to a self-allocated list. Handle AI_V4MAPPED
for pre-Vista platforms supporting getaddrinfo.
* wincap.h (wincapc::supports_all_posix_ai_flags): New element.
* wincap.cc: Implement above element throughout.
* include/netdb.h: Note how AI_ADDRCONFIG is not supported pre-Vista.
Remove superfluous comment.
4815dd49bb