* include/resolv.h: Adjust __libc_res_nquery and __libc_res_nsend

* include/resolv.h: Adjust __libc_res_nquery and __libc_res_nsend

	prototypes.
	* include/arpa/nameser_compat.h: Define T_UNSPEC.
	* nis/Versions (libnss_nis): Export _nss_nis_gethostbyname4_r.
	(libnss_nisplus): Export _nss_nisplus_gethostbyname4_r.
	* nis/nss_nis/nis-hosts.c (LINE_PARSER): Change to also handle
	af==AF_UNSPEC.
	(_nss_nis_gethostbyname4_r): New function.
	* nis/nss_nisplus/nisplus-hosts.c (_nss_nisplus_parse_hostent):
	Change to also handle af==AF_UNSPEC.
	(get_tablename): New function.  Use it to avoid duplication.
	(_nss_nisplus_gethostbyname4_r): New function.
	* nscd/aicache.c (addhstaiX): Use gethostbyname4_r function is
	available.
	* nss/Versions (libnss_files): Export _nss_files_gethostbyname4_r.
	* nss/nss.h: Define struct gaih_addrtuple.
	* nss/nss_files/files-hosts.c (LINE_PARSER): Change to also handle
	af==AF_UNSPEC.
	(_nss_files_gethostbyname4_r): New function.
	* resolv/Versions (libnss_dns): Export _nss_dns_gethostbyname4_r.
	* resolv/gethnmaddr.c: Adjust __libc_res_nsearch and __libc_res_nquery
	calls.
	* resolv/res_query.c (__libc_res_nquery): Take two additional
	parameters for second answer buffer.  Handle type=T_UNSPEC to mean
	look up IPv4 and IPv6.
	Change all callers.
	* resolv/res_send.c (__libc_res_nsend): Take five aditional parameters
	for an additional query and answer buffer.  Pass to send_vc and
	send_dg.
	(send_vc): Send possibly two requests and receive two answers.
	(send_dg): Likewise.
	* resolv/nss_dns/dns-host.c: Adjust calls to __libc_res_nsearch and
	__libc_res_nquery.
	(_nss_dns_gethostbyname4_r): New function.
	(gaih_getanswer_slice): Likewise.
	(gaih_getanswer): Likewise.
	* resolv/nss_dns/dns-canon.c (_nss_dns_getcanonname_r): Adjust
	__libc_res_nquery call.
	* resolv/nss_dns/dns-network.c (_nss_dns_getnetbyaddr_r): Likewise.
	(_nss_dns_getnetbyname_r): Adjust __libc_res_nsearch call.
	* sysdeps/posix/getaddrinfo.c: Use gethostbyname4_r function is
	available.