Don't truncate long hostnames.

When a client connects from an IP address that resolves to a hostname
longer than HOSTLEN characters, the ircd truncates the excess
characters.

Until commit e2004bf0a2c851e7d81fc317b1cc230c9415d3e3, which increased
the resolver's maximum hostname length, this truncation behavior was
masked since the ircd tries to check whether the forward and reverse DNS
for a client's IP address matches. The resolver would try to resolve the
truncated version of the hostname and fail.

Fix this by rejecting a client's resolved hostname if it is too long.

Signed-off-by: epiphani <epiphani@dal.net>
Merge branch 'master' of ssh://github.com/epiphani/bahamut