[CFR] exposable reentrant functions of netdb

[Hajimu UMEMOTO]

Hi,

I reworked the netdb functions in our libc to conform to the Solaris's
API.  With this change, we can expose get*_r(3) to the outside of
libc.  Further, I changed the internal of gethostby*(3) and
getnetby*(3) to NSS friendly.
Please review it.  You can get the patch from:

    http://www.imasy.or.jp/~ume/FreeBSD/netdb-solaris-api-20060405.diff.gz

Sincerely,

--
Hajimu UMEMOTO @ Internet Mutual Aid Society Yokohama, Japan
ume at mahoroba.org  ume@{,jp.}FreeBSD.org
http://www.imasy.org/~ume/