Warn when binding non-local address

See merge request !345

Autoconf fixes

@mvavrusa Could you please test the --with-lmdb=no now?

Looks ok on my system now:

```
  knot 1.99.1

    Target:   linux-gnu x86_64
    Compiler: gcc -std=gnu99
    CFLAGS:   -g -O2 -Wall -Werror=format-security -Werror=implicit -fpredictive-commoning   -fvisibility=hidden
    LDFLAGS:
    LIBS:     -ldl -lpthread -lm  -lurcu

    Prefix:      /usr/local
    Run dir:     ${prefix}/var/run/knot
    Storage dir: ${prefix}/var/lib/knot
    Config dir:  ${prefix}/etc/knot

    Knot DNS libraries:     yes
    Knot DNS daemon:        yes
    Knot DNS utils:         yes
    Knot DNS documentation: yes

    Fast zone parser:      yes
    Utilities with IDN:    yes
    Systemd integration:   no
    GnuTLS:                -I/usr/include/p11-kit-1  -lgnutls -lnettle
    Jansson:               -ljansson
    Dnstap support:        no
    Code coverage:         no
    LMDB support:          embedded

  Continue with 'make' command
```

See merge request !346

Namedb revert

See merge request !342