mount: remove legacy version of nfs_name_to_address()

Currently we have two separate copies of nfs_name_to_address() since
some older glibc's don't define AI_ADDRCONFIG.  This means extra
work to build- and run-test both functions when code is changed in
this area.

It is also the case that gethostbyname(3) is deprecated, and should
not be used in new code.

Remove the legacy code in favor of always using getaddrinfo(3).

We can also get rid of nfs_name_to_address()'s @family argument as
well.

Note also this addresses a bug in nfsumount.c -- it was calling
nfs_name_to_address() with AF_UNSPEC unconditionally, even if the
legacy version of nfs_name_to_address(), which doesn't support
AF_UNSPEC, was in use.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>