First cut at adding local caching to the getaddrinfo support. Still needs work

First cut at adding local caching to the getaddrinfo support.  Still needs work

* fake-addrinfo.h: Delete the unused WRAP_GETNAMEINFO support.
(HAVE_GETADDRINFO) [__APPLE__ && __MACH__]: Don't undefine.
(FAI_CACHE) [__APPLE__ && __MACH__]: Define.
(system_getaddrinfo, system_freeaddrinfo, system_getnameinfo): New functions.
(gaiptr, faiptr, gniptr): Variables deleted.  Change references to use the
system_* functions above.
(getaddrinfo, freeaddrinfo) [FAI_CACHE]: Define as macros to the my_fake_*
versions.
(protoname, socktypename, familyname): Use caller-supplied buffers instead of
local static buffers.
(debug_dump_getaddrinfo_args): Provide a buffer.
(NEED_FAKE_GETNAMEINFO): Define if HAVE_GETADDRINFO is not defined.
(inline): Rework macros to test for C99 and IRIX.
(NEED_FAKE_GETADDRINFO): Define if FAI_CACHE is defined.
(fai_add_entry) [KRB5_USE_INET6]: Support IPv6.
(CACHE_ENTRY_LIFETIME): New macro.
(struct face, struct fac): New types.
(fac): New static variable.
(plant_face, find_face): New functions.
(fai_add_hosts_by_name) [FAI_CACHE]: Check the cache before looking up the
hostname.  Add the looked-up host info to the cache.
(fake_getaddrinfo): Call GET_SERV_BY_NAME instead of conditionally calling
getservbyname or getservbyname_r.  Don't pass AF_INET to
fai_add_hosts_by_name.
(fake_getnameinfo): Define only if NEED_FAKE_GETNAMEINFO is defined.
(gai_strerror): Define if either HAVE_FAKE_GETADDRINFO or NEED_FAKE_GETNAMEINFO
is defined.
(getaddrinfo): Do define function if FAI_CACHE is defined.
(getnameinfo): Define only if NEED_FAKE_GETNAMEINFO is defined.

ticket: 1380
status: open

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@15780 dc483132-0cff-0310-8789-dd5450dbe970