Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- poll(2) support.
- simplify by strdup.
- set ai_protocol in hints to TCP.
- g/c FAITH_NS (no description, not maintained for years)
- warn if connection from IPv4 mapped is reached.
- IPV6_V6ONLY if possible.
- unifdef -UFAITH4.
- drop rsh/rlogin support.
- deal with negative return value from wait3.

Obtained from: KAME

another tcp apps IPv6 updates.(should be make world safe)
ftp, telnet, ftpd, faithd
also telnet related sync with crypto, secure, kerberosIV

Obtained from: KAME project