Avoid DNS reverse resolution for server names (take 3)

Avoid DNS reverse resolution for server names (take 3)

A NFS client should be able to work properly even if the DNS Reverse
record for the server is not set. This means a DNS lookup should not be
done on server names at are passed to GSSAPI. This patch changes the default
behavior to no longer do those types of lookups

This change default behavior could negatively impact some current
environments, so the -D option is also being added that will re-enable
the DNS reverse looks on server names, which are passed to GSSAPI.

Signed-off-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>